Help for brother

Apologies for not posting in the correct forum.

My brother has been dealing with bad bouts of anxiety and depression over the past few months, something he's had since high school but it has really reached a new level. I live away but visit often, and am also available for him to message or call, which we also do often. He lives with my Mum who works full time but also supports him such as taking him to GP appointments. He volunteers 3 times a week but in these past few months has had to leave early some days, with something triggering him (sometimes this might be a particular interaction with a colleague or sometimes he cannot remember why he starting feeling like that). He then very quickly starts spiralling and becomes very distressed with the thoughts he has, leading him to then go walk somewhere and send upsetting messages to my Mum and me. We had an A&E visit last year for this, where we saw a mental health practitioner. As understanding as I was to the situation, I struggled to understand what it was that he wanted from this interaction, such as next steps for therapy etc. (he wanted me and Mum present in the consultation as he sometimes does not want to speak, and I understand this as feeling uncomfortable/embarrassed as well as not knowing what to say). This situation happened again today, and I was able to calm him down on the phone, but it meant Mum leaving work early to go collect him. It is hard for her to manage this when she is working, as well as taking him to appointments, whilst she works a full time job and takes unpaid leave. I am also worried about the stress on her as her physical health is not great and I am concerned that her mental health is not as good as she lets on. I myself am finding it difficult to manage along a busy university course and part-time job. I would never let this stop be from supporting him, and would seek support myself if needed. I always remind him he can call or message anytime. I said initially in the call that the crisis team could maybe help a bit better to talk through this situation, however he seemed reluctant to do this, even when I suggested doing a 3-way call. I am sure it may be he does not want to talk to a stranger, but he also can't tell me why, even when I explain their expertise mean there are better placed to help. He has had ongoing reviews with the GP, with an adjustment to his anti-depressants, but this does not seem to have made a difference.

I know he struggles to articulate what he feels or thinks, and I know this adds further frustration and negative thoughts for him. The same themes in what he says occurs, including usually what he says when he has a crisis as described above. These relate to feeling useless, worthless, that he is a burden to everyone, is 25 living with his Mum and has no job etc. I try to remind him that everyone is on different paths in life, and that the current political, social etc climate makes things difficult for people in our age bracket, as well as the fact that lots of people experience difficulties with their mental health and require varying levels of support, however long it takes. It is not easy for him to reflect on this himself, and usually when I talk him through it he calms down. He verbalises that he needs reassurance at volunteering, and often finds it difficult when his friends do not reply when he messages them about a decline in his mental health (something I feel may have happened today as he mentioned it). I know it is difficult for people to know what to say, as I have been there myself for friends, and as well, people are busy in their day. 

I am seeking an enquiry for a counsellor, which he has agreed to, as there is only so much advice and support I can provide within my knowledge and skills, something he is understanding of.  All I want is for him to get through this, but I know this not always how depression works. Having gone through some dark periods myself, I have been able to use coping mechanisms which he is not able to use eg mindfulness, CBT (he doesn't gel with these approaches). I want him to understand the importance of his place in the world, as well as the fact that we are each unique individuals with different experiences in life, and with this, shouldn't compare ourselves to what other people are doing. I care deeply about him and Mum and wish I had a magic wand to make everything better. 

I suppose this has offered me a chance to off-load, but also I would appreciate if anyone (yourself or carers/family) have experienced this and could offer insight into what could help?