Hard lump on bottom lip?!

I was eating when I noticed a hard lump inside my bottom lip. I cant really see it but I can feel it and when I touch it, it moves. Then on top of that another thing grew but this lump/ball is more visible, clear and smaller. Two years ago I had oral surgery because of something similar in the same spot. Ever since its been growing back and then it disappears.The doctor said this could happen. One morning I might wake up and there it is. A few days letter it will disappear and then months later there it is again. So my question is, is it the same thing?
Should I get it checked out?
The problem is im afraid ill make an appointment to get it checked out and then the day of the appointment it will disappear.
Will the doctor be able to remove anything if it disappears so it wont grow back?
Please Help Me. It doesn't hurt but its annoying.