If you believe this is simple impingement, and you don't think the tear is a factor, up the ibuprofen to 800mg x 4/day for 5 days, and then start the Starr rehab with presses, making sure to shrug into the lockout. But add this as a warmup: hang with a pullup (prone) grip for several 15 second reps from the bar, then several more with a chin grip (supine). Then do a couple of sets of 20 light lat pulldowns with a chin grip. This should prepare the shoulder capsule for the pressing.
Do presses only for 3 months after this is healed, and then re-introduce benches with a moderate grip, and from then on do your benches 1:1 with presses. This keeps the shoulder in balance, and prevents these kinds of problems.