1st - Take a deep breath and relax.
It can be so overwhelming. We went from local psyc. testing to neurology then Mayo Clinic and now referred to the University of Minnesota.
I was scared at first but I know that it won't change things but just help with how we approach things with our son. Get a notebook and write down anything you can think of. Diagnosis, treatments, behaviors, therapy, support groups, educational materials, etc.
I wish you the best.