Have a 4yr boy that is a picky eater and has behavior problems

Well we just found out in the summer time he has asthma, and some allgeries is peanuts and soy, some food that he likes like peanutbutter , but he wasn't a picky eat until the age of 2 1/2 he used to eat everything off his dad plate now he will just he cracker, chex cerceral rice kind, sometimes grilled cheese , waffles , and some junk foods, but he loves milk. i had him eating mac and cheese but he got sick with 24 hour flu bug throwing up , and now i gave it him once he gag on it and spit it out. he won't eat meat at all, is this a texture thing or more behavior, also he has been test for autism, had mri done nothin found wrong with that took him to a school that test for it they said that he has behavioral problems they didn't give me paper off results or anything i can do for him. he has had speech too still does