@Newmum912. Totally random question but have you checked or Dr looked to see if he got tongue tie?
As long as he getting fluids I wouldn’t be worried about water one of mine refused unless I held my cup to him and then most of it went down him.
DS liked those milk ice lollies which I’d hold. Food time was very messy affair.
The Dr sounds like using that old book of bad school advice.
I can imagine that food is very stressful time for you both. Do you have routine meal times or is it random. Am much as you try to appear chilled kids know and simplest thing has to happen ie mine gagged on banana and that set tone for all foods for awhile so took lots of coxing.
Another idea if not tried something like sitting on sofa with him watching tv you eating ie a banana paying attention to tv - not offering him any, kids are very inquisitive and there is no pressure on you or him.
Another idea is to put food say on coffee table that ok for him to eat, it really can be small steps first him getting used to seeing it there but no pressure to eat, then he might start touching it, squeezing it etc. Make sure it ok to have it where u don’t mind mess.
Another trick is to get him to smell, you could do that with yoghurt he eats, get him to smell it & keep doing that. You do it too let mummy smell your yoghurt - kind of diverts focus of just eating. After few days ask him to smell a food but don’t expect or ask him to eat it. It’s kind of leading horse to water trick.
Lastly cut yourself some slack, take deep breath and remember you will get there, it really is trial & error. Do check he has no issues with mouth - lip or tongue tie.