i was jerkin off hardcore last night, probably for a continuous time of about 48 minutes. all with the same arm, my left one. after i finished, my left shoulder was on fire and one of my forearm flexors hurt like a bitch. i woke up this morning, and now my flexor carpi ulnaris m. is fucking killing me. it hurts to type and shit. i'm gonna take a day off from the gym today, i feel like i might drop a weight on myself due to the pain. any exercises you guys can recommend to fix this? i'm thinking some sort of stretch maybe?