My son, 16 LHP, had TJ surgery in February. He is a week shy of 8 months and is working through the mound phase. He has had a relatively smooth rehab, but it seems like every time he moves to a further distance or increases the number of throws he has some pain while throwing, with soreness the next day. It usually resolves by the end of the week. He recently had severe pain in his triceps that went away after he took the next session off. This occurred during a session that he started off saying that his arm felt the best it had felt. Of course, he pushed the velocity a little and his body reacted negatively. Definitely agree with Glenn that you should consult your medical professionals if you think something does not feel right, but expect some pain and soreness throughout the process. I know this has been said over and over again, but follow the rehab and throwing program to a t.