Any change you make should ideally be done one at a time so that you can keep a record of the effects and see what works and what doesn't. If you do more than one thing at a time, you would never know which thing made the difference. You could wind up giving your child expensive supplements or keeping them on a restrictive diet for no reason.

One tsp of cod liver helps with eye contact. Mix with sprite or lemonade if child does not take it straight . My dan dr recommend . It helps my son.

Always remove casein first as that usually has more visible and immediate impact for some kids (also need to remove soy as that can produce peptides similar to casein). Gluten sensitivity is much lower in ASD. Give two weeks between adding new supplements so can observe any negatives or positives.

Thank you for the answer.
Any things you may say about Gluten free and Casein free?
I wonder if these diets and supplements can be all done at the same time?

Remove dairy milk, get fish oil supplement with high DHA/EPA and start supplementing multivitamins or B complex. Any or all of these can result in vast improvements for some kids. Good luck.