autistic burnout

I'm writing this on behalf of my partner, who is awaiting their autism diagnosis next year. He realised he's autistic after doing research for a character (he's a writer) and suddenly found something that explained his entire life (and his lifelong suffering). He is now, about a year and a half after realising he's autistic, suffering from a really intense burnout. It started in January, when university became too much. He'd gotten behind on courses due to getting sick and general overwhelm, and then completely burnt out and couldn't do anything anymore. Since then, doing anything at all has been too much. Days in which he'd push himself to do the dishes would end up in him feeling dizzy and drained and months later, he'd struggling to find his old self back. He can't do the things that are important to him, like finding the energy to write. He's often struggled to write, due to depression, but he's always managed to push through it, but not with this burn out.

I read that many people experience autistic burnout after having masked their autism their entire life (he's 30) and this would make sense for him, especially as he went back to uni during the same period after having not been in such a setting for 10 years.

I have barely been about to find research on autistic burnout, how it works, what it actually is, what to do to help recovery from this kind of a burnout... and he doesn't have a therapist/coach for his autism now as he'd still awaiting diagnosis, so we don't know who to ask or where to go to learn more about this to help him, as this is causing so much suffering it might well burn him out all over again!

Does anyone have experience with autistic burnout? If so, please share your experiences! And if anyone knows of any articles, books, blogs, anything really, that could teach us more about it, that would be amazing.

Thanks so much! Hope you all have a wonderful weekend!