how often to you block shots with your shoulder? that might affect it also, i did just that more often than usual yesterday and my left arm is killing me today.
could be that, you might feel it in your elbow too if thats the case. are you stretching at all after you're done? i know its not your muscles that hurt but stretching would still help keep the joint loose
both, feels like my rotator cuff! just bought some glucosamine to help the joints! Sucks I gotta spar again end of this week, hopefully it heals by then.
obviously i cant tell how bad it hurts but if its pretty bad after you spar maybe see a doctor or at least talk to people in the gym about it