Great advice from all above. In addition, I’d like to add a few comments.
As someone who had rotator cuff surgery last year, I know all too well what you are describing. First, a suggestion would be to see your Doctor. RTC issues should not be taken lightly. And if you have a tear (like I did) constantly bringing your arms overhead only makes it worse. Other things should be ruled out. Second, the best pose to stay in and work on is Adho Mukha Svanasana (Down Dog). Every single one of my rehab exercises contributed to my recovery, but Down Dog helped the most. Something for you to test on your own or with a teacher: In down dog, where are your shoulder creases? Are your elbows bent out to the side? For many students with tight shoulders they tend toward internal rotation instead of external with their shoulders. This will show with the elbow points sticking out to the side. Usually this is due to weakness in 2 of the rotator cuff muscles the Teres Minor and Infraspinatus. They both control external rotation and help to protect the shoulder joint when you bring your arms overhead. Down dog strengthens these two RTC muscles. So, in down dog some things to think about. Where is the weight on your hands? If the weight is more toward the thumbs, you are inclined to internal rotation. If it is more toward the pinky, it’s external. What you want is balance. To get this, as you come into down dog, you’ll want your elbow creases facing your hands (really the thumb). Play around with internal and external rotation in down dog to get a good feel and to see where your creases are aligned. Once you get that, press a bit more firmly into the thumb and index finger. This will bring and keep you into external rotation.
And while you work on Down Dog, don’t bring your arms overhead. You can bring them out in front, in line with your shoulders, but not over your head.
Just some more things to consider! Let us know how you do!