basically ive been reading some previous threads on shedog about this and the same thing happened to me yesterday on the mat: My rolling partner was going for a triangle and I managed to squeeze my lose arm in and started working my way back into his guard. He then had a very high guard on me and took my right arm and bent it over his leg to the outside of my body. We both heard a distinct pop in my elbow. I have full mobility but when I put resistance against it, it feels like its going to give out (if my arm is at a 90 degree angle with my elbow against my hip, it is the left and right movement that causes discomfort, not the up and down). So the horizontal movement is the problem? I feel a tenderness at the base of my forearm, right next to the elbow. Any advice as to what I did? I read it might be an UCL / MCL sprain?