Is this new? If so, is the Prozac of Concerta new?
Both can cause hallucinations in any kids. I know first hand. They often go away once the medications are removed. Again, I know this first hand. 40 mgs. of Prozac is a high dose. I believe 20 is a normal adult dose. Not everyone can handle Prozac at all, let alone 40 mgs. And with Concerta, in my opinion, bad mix. I have no idea what Amatadine is, but if it's activating, no wonder he's hallucinating.
As one who has taken medications since age 23 and I'm 55 now, I know that often the medications that are supposed to help end up being the problem. Your child is on a lot of medications for a simple diagnosis. of Aspergers. I would wonder about them. A lot.