I hope that you find someone to help him, poor lad.
While clearly other issues cannot be ruled out I can say from my own experience that doctors were convinced my issues were entirely psychiatric (even though I had no past medical history prior to the bite and rash). I actually had a 'consult' (informal, out of office) with a family friend who is a psychologist because they had me convinced I was mad. He told me I 'just' had lyme. The 'nutty' stuff you describe were my psych symptoms too - amongst others - including the horrific nightmares and EMF sensitivity.
I did feel much worse when I started treatment (both abx and herbs had the same worsening effects). I didn't really make any headway until I sorted out my detox problems (cause by those pesky gene mutations). I think any treatment initially cause too great a toxin load and I couldn't cope mentally, let alone physically, and it all got a bit messy. I also think the bart played a big part.
What I guess I am saying is that it is quite reasonable that the lyme and co is the root cause of the problem and treatment for that would be the starting point if that is what he has. But to watch for the fact that treatment can exasibate the problem so a competent psychiatrist would be a good thing too.
It is a real tricky one and I hope that someone here can help you to help him.
Edited to add - julymorning is on it before I finished typing. This forum rocks