PDD-NOS and vitamins/supplements?

I have a seven year old child with PDD-NOS and ADD. How do I know which vitamins/supplements I should try with her? All the information I've read has left me feeling overwhelmed. Fish oil, B-6, probiotics, amino acids....just to name a few. I'm just not sure what I should start her out on, how many types I should try with her at once, and are there any bad combinations that I should stay away from?PDD-NOS and vitamins/supplements?
This question would be best for your child's pediatrician. If your child is on any medications, you want to make sure that certain vitamins and supplements don't interfere with them. It's also important to talk to your pediatrician because your child may not even need them.