Pediatrician isn't being helpful ADVICE PLZ

my 3 year old has stopped eating completely. This has been on and off for 2 months but he was getting better until 3 days ago. He won't eat a single bite of food and screams like he's being hurt if I offer food to him or sit him in the chair to eat a meal. This is a kid who was never picky and always ate great. We've had thousands of dollars in tests done and they say he's fine. But he literally won't eat a single bite of food and it's making him absolutely miserable and impossible to deal with. He will ask for food and then refuse it and scream so hard he vomits.

I really need advice the Dr keeps telling me to ignore it bit he literally screams all day worse than a newborn.