HI there... as described base of tongue is actually down your throat. You are describing oral tongue. And usually oral tongue tumors tend to originate at the side or under the tongue in the mouth. Now doesn't mean it's not a tumor (thought it could be an infected area or scar tissue from radiation). Best to have it checked out to be on the safe side. Sometimes the tumors aren't even visible as they are inside the tongue. Hope it's nothing... definitely have it looked at. hugs and welcome.