Having a child with additional needs is overwhelming. When you're in that stage of not knowing what's going on, unsure of the future, overwhelmed, at your wit's end, worried - it's truly awful. You're not full of fail. You're reaching out for help.
Psychiatrists are MDs so they can prescribe. You're the parent, so you can decide if you medicate.
If you have a child who is multiply-complicated, you need professionals with well-developed and trained clinical skills, and possibly a multi-disciplinary team. Wherever you're living, I would figure out who provides mental health services, children's services, special needs services and call those organizations and ask questions.
GL to you.
This is a really good book:
http://books.google.com/books?id=DmUpCSlnmKAC&printsec=frontcover&dq=syndrome+mix&hl=en&ei=V0zdTdn8MIX4sAPf-dWqBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CDAQ6AEwAA#v=onepage&q&f=false
I found this book very comforting when we were still in the wtf is going on stage :):
http://books.google.com/books?id=kPtmPoUAfXMC&printsec=frontcover&dq=when+the+labels+don't+fit&hl=en&ei=hUzdTZjOLYjCsAPA9ZmVBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCkQ6AEwAA#v=onepage&q&f=false