Amanda,
I agree with Brian, I am not sure that anyone can feel something 2mm-did he say 2cm possiblly? Scans do not detect anything smaller than 6mm I believe, so I would be surprised if that is something that could be felt through touch.
Don't be embarassed if it is nothing. Anything that doesn't go away in a reasonable time frame should be checked out! That being said, if it doesn't go away after this, please follow-up and be persistant! Doctors often want to dismiss young people and oral cancer because it is rare-but it does happen!
Sarah