Can make the disco arm a bit tricky.
Ideally you will need hands on treatment to speed up the recovery, a sports injury type therapist would be best in my opinion
You will need to start to strengthen the rotator cuff muscles (assuming that`s what it is) ~ so what you can do is arm down by side, elbow bent 90 degrees, rotate the lower arm outward as if you were trying to do a back handed slap, but you keep your elbow in to your side and with your other hand supporting and blocking the movement below the wrist of your injured side so that the arm does not move, this will work the muscles but not aggravate the tendons. Depending how irritable it is, probably do (2 sets of about 15 repetitions) 3 times a day. After a week and assuming it has not got aggravated you can add 1 set of 15 reps of rotating the arm inwards, but blocking the movement below the wrist. Gradually build up the pressure, hold for about 5 seconds then gradually release the pressure. As these are more postural type muscles just go to about 70% effort, just use an amount of effort that is pain free otherwise.
Keep it as mobile as possible throughout the day. Other exercises are available for this condition as well.
I
strongly suggest you do
not go into pain with your movements or exercises at the moment as this can possibly inhibit the muscles around the joint, making it more unbalanced and so more likely to further aggravate these tendons. As time goes on and it is less irritable you can add resisted movements, ideally eccentric (controling the weight returning to the starting position), with these you can start to go into a bit of pain in the last 5 or so repetition.
Good luck
