What is this lump under my jaw on the left side that has a pulse and moves whenever i try to touch it?

ok so every once in a while i get a very sharp pain underneath my jaw on the left side and i decided to feel around and see if there was anything there. when i started feeling around inside my mouth and on the outside i felt a 1 to 2 cm lump that has a pulse and moves whenever you roll it around. it hurts extremely bad and i need advice on what to do. and im in alabama at the moment but im going back home to oklahoma in a few days is this urgent?????