M.P.
I don't know what community you live in but in Livingston County we have LESA (Livingston Education Services Association). LESA provides services to families with autistic children and other children with special needs.
There is a website called ourspecialkids.com that helps parents as well.
I realize it is difficult to get healthy food into an autistic child, but don't give up. You will see your child develop better and the moods will be more even tempered as well.
Good luck and God Bless.
M.