IMO Usually causes by the elbow to far away from body and not keep the wrist cocked back till after contact (deep V) when hitting balls from backcourt which from bad stroke technique that pulls strain on crazy bone nerve. ( Usually called flying elbow)
I suggest you watch several instructors on utube on grip ( usually continental for backhand and continental or eastern grip for forehand depend on you’re skill level? Utube is great, you can learn something in weeks where use to take months.
This injury also may be from another sport like golf, tennis, and racketball? Not going to be easy changing you stroke once you been playing awhile, you really have to practice the swing to hopefully change it.
https://www.youtube.com/watch?v=NJUKLbzM0Bo
You can see other examples to right, choose one that beat fits you’re level.