Some time ago, I could feel a lump on the floor if my mouth. It was a liquid-filled lump that eventually burst and then for two days there was a whitish painless lession which later disappeared. Several days later, the clear lump came back again, and the same happened. Now I can feel that the lump is popping up again. It always pops up next to the salivary gland under the tongue. Is it dangerous? Could it be a virus? It's never painful.