Inflammated supraspinatus and AC bursitis is very common and is an impingement syndrome. I presume this is your problem?
First step is to stabilize your scapula. Make SURE that the serratus anterior is tilting your scapula posterity during exercise.
Next step is making sure all the muscles of your rotator cuff are firing correctly.
Third is eliminating tightness in humeral elevators. Triceps long head, both biceptal heads, coraco brachialis, deltoid dysfunction (if supraspinatus is inhibited), basically every muscle that have potential to pull the humerus out of the glenoid fossa (I think I mentioned all of them)
Hope this helps