answer:Maybe ‘Tennis elbow’ ? Without a check, impossible to say for sure. Are you a sports person, have you done anything with that arm lately that has been stressful on the joints? It could be anything, raking the yard, walking your dog, throwing a ball, lifting something heavy, anything. It sounds like the joint or ligaments are strained. Try resting it, take Ibuprofin, maybe icing it and if it doesn’t feel better in a week or two, go to the doc.