Hi. wow you guys have been through a lot. I wonder about ptsd with him too??? those tests have lead to big surgery and pain for him so could that be part of it?
The other thing that jumps out at me is maybe something happened during or after surgery... did he suffer a brain injury that they did not pick up on? I would want to see a neurologist to make sure that the sudden change when he had surgery was not the kick start to something. Sounds super suspicious to me and if I got a client who gave me this history I would for sure refer for neuro. I would recommend a pediatric neuro not a general and one who has experience working with brain injury, not the seizure specialists, etc. They tend to blow off kids like that, oh, they may do an eeg, but then if nothing shows...they dismiss you. I think an MRI and/or pet scan could be really useful to you. Just MHO of course.
OF course regardless, you have some pretty serious stuff going on and I can really relate. A neuropsychologist evaluation will help you sort through the emotional and family history, the medical history, and these specialists help connect what is going on between behavior and how our brains work, both emotionally and medically/developmentally.
No worries about being "long winded" if you get kicked off for that I and several others would be too. We all express ourselves differently and the fact is, there is a LOT to talk about here!
He is a danger to you and himself, he will feel terrible about himself it sounds so it is wonderful you are seeking help. HUGS to you and your family!