I had several similar experiences with my back molar, gums that was infected in 2010 after radiation. Needed the hyperbaric, antibiotics, but never had the tooth extracted. It flared up a few times since, needed biolsy on tongue as a precaution, and most recently last month during treatment, which was examined, CT scan taken, but this time was concluded to be mucositis, and ulcer from biting my cheek, but I still need to take the tooth out at a later date. Oral Antibiotics may take a while to work. Rinse rinse with baking soda, leave out the salt if it burns, use magic mouth wash, and avoid irritating foods like spices, acids, sharp texture or difficult to chew foods, so not to irritate the area or cause more pain. Good luck with the biopsy.