Where to get support for a burned out 8 year old?

She is alternately clingy, anxious, and furiously angry

She is probably on a spiral into survival mode. 

First, I'd let go of the word Clingy - language is important. Small ducklings literally follow their parents around. All small animals hang all over their parents. It's normal in the wild. In an ideal world we'd get more than enough time with mum and dad to exit as soon as possible and maybe call on a Sunday, but that's not how the human world is designed currently. Parents work, life has exhausting demands, parents feel guilty but also depleted, kids experience separation anxiety and deal with it according to their genetics and personality. But sometimes the only person in the world who you genuinely feel connected to is a child/parent. Even in the best of situations no one seems to cope at 40 and beyond when their parents pass. It never ends. If she wants to be near you it means you're a good parent! Cruel, irresponsible parents don't have younglings swinging off them, so unfortunately, it's part and parcel :)

On her being anxious and furious - this is also a modern trend. Sensory overwhelm and Monotropism are the main things to understand.

We feel intensely - everything. And everything can seem 'too real' according to the Bayesian Model. I was startled by a squirrel today. So silly - but it has something to do with a difference in ability to predict, apparently. However, I am always calculating possibilities - which include all the ways I could die in a given moment. All the great things that could happen too. It's a normal state, but it can keep me awake at night if I don't make an effort to engage in something enjoyable like fiction or sudoku. We can't dull our senses like our peers, and we sense-perceive with a potential to become proficient, not just external but also internal emotions with a greater intensity. One thing I like to suggest with kids is maybe learn safe ways to indulge the senses and like any potential or skill, begin to use them to calculate better - and protect them as well. A fun thing here would be once a month chocolate tastings or apple tastings. Maybe an evening making shades of colour. Each degree of difference can be fascinating and it can help her recognise the enjoyable aspect of having heightened attenuation.

Monotropism is a great explanation of how we think and perceive, but the most important thing to note is interruptions are a kryptonite and this won't ever change. Help her learn to set and stick to boundaries. I describe this like waking a sleepwalker. Most likely this can be the issue with a sibling. If she's continually interrupted, it will feel like sleep deprivation torture. It will interfere with everything including the ability to grow. It seems that it has something to do with a different relationship with time and the ability to just switch into a flow-state. This has a potential as well. Getting lost in a microscope, in making music, in any observation or production: we can thrive if left to it with only occasional alarms to remind us a loo break and to eat!

Minding these few things and helping her thrive with them can lead to a much better 'flow'. 

I will say, there is a good deal of research out about the issue of GABA in Autistic individuals. I have found that Nootropics help (just a mushroom compound). Perhaps we are a 'model of human' that in a tribal setting needed less GABA so to be that alert system when danger was about. GABA is responsible for shutting down thought loops and to keep the brain from spilling from excitement into anxiety. I have found that being continually bothered until I resolve an issue has driven a creativity and a desire to learn. But, when young it's dreadful, we can't yet access physics and biology or sociology and ethics to understand how we're impacted by the world around us. 

She is alternately clingy, anxious, and furiously angry

She is probably on a spiral into survival mode. 

First, I'd let go of the word Clingy - language is important. Small ducklings literally follow their parents around. All small animals hang all over their parents. It's normal in the wild. In an ideal world we'd get more than enough time with mum and dad to exit as soon as possible and maybe call on a Sunday, but that's not how the human world is designed currently. Parents work, life has exhausting demands, parents feel guilty but also depleted, kids experience separation anxiety and deal with it according to their genetics and personality. But sometimes the only person in the world who you genuinely feel connected to is a child/parent. Even in the best of situations no one seems to cope at 40 and beyond when their parents pass. It never ends. If she wants to be near you it means you're a good parent! Cruel, irresponsible parents don't have younglings swinging off them, so unfortunately, it's part and parcel :)

On her being anxious and furious - this is also a modern trend. Sensory overwhelm and Monotropism are the main things to understand.

We feel intensely - everything. And everything can seem 'too real' according to the Bayesian Model. I was startled by a squirrel today. So silly - but it has something to do with a difference in ability to predict, apparently. However, I am always calculating possibilities - which include all the ways I could die in a given moment. All the great things that could happen too. It's a normal state, but it can keep me awake at night if I don't make an effort to engage in something enjoyable like fiction or sudoku. We can't dull our senses like our peers, and we sense-perceive with a potential to become proficient, not just external but also internal emotions with a greater intensity. One thing I like to suggest with kids is maybe learn safe ways to indulge the senses and like any potential or skill, begin to use them to calculate better - and protect them as well. A fun thing here would be once a month chocolate tastings or apple tastings. Maybe an evening making shades of colour. Each degree of difference can be fascinating and it can help her recognise the enjoyable aspect of having heightened attenuation.

Monotropism is a great explanation of how we think and perceive, but the most important thing to note is interruptions are a kryptonite and this won't ever change. Help her learn to set and stick to boundaries. I describe this like waking a sleepwalker. Most likely this can be the issue with a sibling. If she's continually interrupted, it will feel like sleep deprivation torture. It will interfere with everything including the ability to grow. It seems that it has something to do with a different relationship with time and the ability to just switch into a flow-state. This has a potential as well. Getting lost in a microscope, in making music, in any observation or production: we can thrive if left to it with only occasional alarms to remind us a loo break and to eat!

Minding these few things and helping her thrive with them can lead to a much better 'flow'. 

I will say, there is a good deal of research out about the issue of GABA in Autistic individuals. I have found that Nootropics help (just a mushroom compound). Perhaps we are a 'model of human' that in a tribal setting needed less GABA so to be that alert system when danger was about. GABA is responsible for shutting down thought loops and to keep the brain from spilling from excitement into anxiety. I have found that being continually bothered until I resolve an issue has driven a creativity and a desire to learn. But, when young it's dreadful, we can't yet access physics and biology or sociology and ethics to understand how we're impacted by the world around us. 

JuniperFromGallifrey said:

I am always calculating possibilities - which include all the ways I could die in a given moment. All the great things that could happen too. It's a normal state, but it can keep me awake at night if I don't make an effort to engage in something enjoyable like fiction or sudoku. We can't dull our senses like our peers, and we sense-perceive with a potential to become proficient, not just external but also internal emotions with a greater intensity.

Have you tried mindfulness? It seems a very practical solution in your case and I found it returns a great deal of capacity to me when my mind is racing:

https://www.mindful.org/what-is-mindfulness/

Mindfulness is the basic human ability to be fully present, aware of where we are and what we’re doing, and not overly reactive or overwhelmed by what’s going on around us.

Mindfulness is a quality that every human being already possesses, it’s not something you have to conjure up, you just have to learn how to access it.