Hi there... okay I don't want to feed your fear. Realistically speaking anything is possible. As paul said three weeks out pain is possible due to healing and scar tissue. It depends on the size of the area removed an how quickly you heal. I would say the pain should be gone within another week.

You do have reason to be afraid, I hear that, since you have had some uptake on your scans. However scans also pick up inflammation, infection and healing areas that are hypermetabolic.

Does cancer grow only on the surface? No, it can grow in the muscle or wall of the area/tongue and be invisible. Usually though when it gets big enough to cause a problem, even if it's hidden under the surface, there will be some indication. possibly a protrusion, small sore, lump... etc.

If you have a large area that should be biopsied then often doctor will take a few samples from places that cause concern for them.

I want to say wait and see if you heal. However trust in your dr. is important - if you are concerned they missed something go to someone who knows oral cancer.

best of luck.