Ok Garry it sounds like what I had, need to see Dr who will send you for a ultrasound on the shoulder which should show up a tear in the ligament. I had a 12mm full depth tear in my left shoulder. Had it operated on 3 weeks ago, still got another 15days in a sling, then a few more weeks of physio before I can use it again. All told approx 3 months off work it will involve, I struggled for a few years but once I sold my business I decided to get it done. Worst part is the sleeping with arm in a sling, gives me the s##ts but it is now on the mend. First week is probably the worst for pain, the first couple of days was fine, they put in a morphine pump and tank which was held in my sling, this started to stop after 48 hrs and it did hurt, luck Dr who removed my pump gave me a script for pain killers. Have a few exercises to do 3 to 4 times a day to keep movement in shoulder. The trick is to heat shoulder with heat pack before exercises and then hit the shoulder with a cold pack straight after to contain any swelling, hospital Physio told me that trick, the physio who setup my exercises never mentioned heat and cold.
Just gotta control the STIR CRAZY symptons, not being able to do anything SUCKS.