Hi! I have this thing under my tounge, it kind of looks like a small blister but not sure what it is. I've had it for a couple of weeks now. It goes away sometimes and then it comes right back at the same place. It is not really painful but it hurts a bit under my tounge when I have it, not in the same place as the "blister" but still. What is this and how can I get rid of it so that it won't come back? Thank you for the help!