OK, mistake number one...not seeing your dentist who is used to looking at soft tissue abnormalities as a matter of routine for three years. Go to an oral surgeon and get this thing checked out. The fact that it is painless and not resolving makes it less likely to be a canker sore (herpes simplex). Herpes simplex sores which most of us get resolve on their own without treatment in 10 days. They routinely hurt like Hell when you get anything in them like lemon juice etc. An oral surgeon is a doctor who starts out as a dentist, and then goes back to school for a few more years to get his surgery specialty degree. These guys do complex facial and oral cavity surgeries and are accustomed to looking at abnormalities like yours. An ENT is a specialist in the ear nose and throat. For all the good guys out there, I had two ENT