Sorry to hear you are struggling
Things to consider would be are you taking your prescribed antacids medication from your surgeon?
Has this only been since you have been on puree food? was nutritional liquids OK? if so go back to liquids, suck some ice, allow any irritation to settle and re try puree again in a few days – being mindful of the 20+ rule (this is still applicable even on this stage) and work with really small portions/mouthfuls and build this up gradually
Have you had a call with your providers nutritionalist yet? if not call your provider and book one in
You could try some gaviscon or chewable Rennie to see if this helps settle things down
Are you drinking enough clear fluids – 1.5ltrs is minimal daily
Hope this helps xx