My son is 4. He vomits after drinking. He prefers to drink over eat. He would throw up 20 times a day some days. I chased him around with Clorox wipes and paper towels.This is actually how he came to be diagnosed with autism. After much testing, no medical reason was found for his vomiting. It was suggested I have him tested for autism. He also is high functioning. I agree with others though, you should see a GI to rule out any thing. I am told my son’s issue is a behavioral one in which he will have to have therapy for. Good luck to you. Hang in there it can be concerning.

Have you considered that the vomiting may be indicating severe constipation? We encountered that. He was still having dirty diapers so we didn't suspect.

my daughter's ABA therapist mentioned to me that a lot of kids with ASD are picky eaters. Have you tried to do ABA therapy for your son? I know that ABA therapist help with introducing new foods. You should look into it. It takes a while for them to like certain foods.I hope this helps

We also have an issue with eating, but not vomiting. He does get hiccups where I can tell he has reflux. You might want to test for GERD if he is vomiting. Pediatric gastroenterologist can test.

could be a sensory thing - textures and smells.