Autism Recovery is possible!

Gluten can take up to a year to get completely out of your system, but the general recommendation is 4-6 weeks completely 100% gluten free. If you don't notice any difference try reintroducing it and see if you notice and decline in behavior. If not, then there's no point staying gluten free.

Casein takes only a few weeks to get out of your system. If it's been more than a few weeks completely free of dairy, then try adding it back and see.

At this point I'd suggest dropping one thing at a time (or in the case of gluten or dairy, re-adding one thing at a time) at the rate of 1 every 2 weeks. If you notice any decline in behavior go back to what you were doing and give it a couple of weeks and try taking out the next thing.

Biomedical treatment of autism seems to work best with those who have digestive issues to start with - did your son have severe constipation or diarrhea? Some have success with the bio-med approach, others do not. No point in continuing with a treatment if you're not getting any noticeable improvements.

And in case it doesn't go without saying - biomed isn't a cure-all even for those it works for and you need to continue with ABA and other therapies regardless if biomed works.