I believe that the body knows which nutrients it needs, and it should be possible to understand if you need a particular mineral-vitamin through its taste (if you crave that taste you need it, if it gets you nauseous, you have too much of it). This is why I "taste" supplements. I know this might sound crazy, but I think it's true. I think taste sense is much, much more sensible than what is commonly thought. After all we rely on it to get the right nutrients when we eat. If you dont trust your senses, what should you trust? A cat can feel a medicine in its food immediately... Ok, so this sounds already ridiculous but its not over yet, it will get even crazier. In my tasting of all vitamins and minerals I found one that I really "craved" was vitamin B6, and another crazy thing is that after eating it there is a strange sinergy (i.e you get pretty hungry) to eat it with magnesium (as in peanuts). [I dont take magnesium from supplements I think they are quite dangerous, if I take just 200 mg I can be very dazed for a whole day].

Now I read that B6+ magnesium is used a lot in treatment of autism...

Ok, I understand this is a bit too much to believe and I probably lost all my credibility but I suggest you to try some B6 and see how you do with it. The Tolerable upper limit is 100 mg, so 50 mg should be fine (this is, however, 25 times the RDA). To me, it does great.

Of course you should not neglect the other B vitamins in the meanwhile.