How can someone overcome the persistent pain in the area of crown lengthening?

Hello doctor,

Five years ago, I underwent a re-root canal treatment redone on the left molar and crown lengthening behind both the right and left molars. Went to the dentist to replace the crown, and the dentist advised crown lengthening about 14 days before crown cutting. The crown lengthening was done behind the right and left molars. However, I am still experiencing pain on the left side while eating and swallowing, as my tongue touches the area each time. I went back to the periodontist because of the pain. He said he was fine in a few days, and there could be an ulcer at the numbing spot. It had been four more days, and the pain was not subsided. I took the full set of prescribed antibiotics and continued to use the mouth wash that was prescribed since the day of the procedure. I had to take 800 mg of Ibuprofen and Acetaminophen every six hours to make the pain bearable. Acetaminophen (Tylenol) was not advised to take with Codeine since I am still nursing my younger one. Is this a normal part of healing with a crown lengthening, or could it be there with something which could cause more pain in this many days?

Kindly help.