Hi, I Have Been Stuck With A Constant Pain In

Hi, I have been stuck with a constant pain in the crease of my left arm. It has been present around 3 weeks, hurting to extend my arm and clench my fist. In the last few days it has started to hurt constantly, even when my arm is still (the worst pain in on the inside crease of my arm) it is even painful to touch. I am currently not taking any painkillers for the pain.