Hi Dear,
Welcome to HCM.
Understanding your concern.
As per your query you have bubble of fluid hanging down from roof of mouth after eating pizza is because of pizza palatal burn. In-gradients of pizza such as hot cheese, pizza sauce, or oregano flakes cause scalding burn and damage to extreme sensitive mucosa of
palate and at least one flap of damaged skin tissue hanging down from palate.
Need not to worry about it. I would suggest you to apply ice on it immediately and put pressure on damaged mucosa. It will stop pain and inflammation.
Gargle with saline water. Avoid sharp, oily and spicy food.
Avoid touching of tongue on palate and don't prick it with any pin or object.
Apply topical analgesics.
Well saliva in mouth act as natural healer and your symptoms will resolve naturally.
If symptoms keep son persisting visit
dentist once and get it examined properly.
Hope your concern has been resolved.
Best Wishes,
Dr. Harry Maheshwari