Hi there.... okay my story in the nut shell - see if you find any similarities. I had a bad molar for years (mostly filling) the filling fell out quite a few times. It was sharp. Rubbed up against the underside of my tongue. A visit to the dentist around 2001/2 He looks under my tongue.. sees a white patch refers me to an oral surgeon.
Oral surgeon removes it and sends it for a biopsy. It comes back thickened skin (like a small callous to protect it from that tooth.
Jump ahead about 7 years.
I have that tooth capped. Then I start having pain. So I repeatedly go back to the dentist to have the damn cap filed down. This goes on for a few years. Finally (at this point my tongue is VERY painful when I eat) I go to my dr. and tell him. He immediately refers me to idiot 1 (an ENT) Idiot 1 - arranges a biopsy (after taking a full medical history - see below) The day of the biopsy he looks in my mouth and says I see nowhere to biopsy... no open sore, no white patch just an angry red tongue that is SORE (the level of daily soreness varies with foods and what not, so it was never sore and getting worse... just sometimes it's worse than others) he says... well I'll just grab a random patch. (he's an idiot because clearly he has minimal knowledge of oral cancer and does NOT do a thorough examination)
He does - results - irritated skin. nothing more. Not even mild displasia. Now if he had felt my tongue he would have felt a small lump inside.... I thought it was scar tissue from the removal of the thickened skin. He didn't even notice it. He did not tell me to come back if it didn't get better - he suggested food allergies??? and / or irritation from the cap.

Negative biopsy.

jump ahead ahead 2 more years... problem ongoing.
I have a second cap put in behind the first - my tongue loses it!!!!!! It goes from sore on and off to EXCEPTIONALLY SORE ALL THE TIME. My Dentist says - have it biopsied again. I go to my dr. and he refers me to idiot 2 (another ENT)(he's an idiot because he has the beside manner of a sadist) and he says it's lichen planus but does want to do a biopsy. He goes deep. Without freezing and then tells me I can wait for him to get back from vacation (a month later) to book an appointment and get my results (that's reason two he's an idiot)

I told him I wouldn't wait that long and found out from my dr. 10 days later that I had oral cancer. By the time Idiot 2 got back from his vacation, I'd had two cts, and an MRI and a referral/appointment - with a top notch ENT/Surgical oncologist at the local cancer center. A month after that I was in surgery.

NOT all ENTs are made the same. My cancer is HPV- I have no precursors for it. Thankfully because I was in good health my body managed to contain it for as long as it did. It was considered well differentiated (thank GOD) in my tongue, but jumped to a node very quickly after the biopsy. And the node was well to moderately differentiated.

Do keep a close eye on the area. Have it looked at repeatedly and if you aren't getting answers or satisfaction... see someone ELSE.

best of luck