From the physio I've had in the past. The general rule seems to be start working the area immediately, but in stages.
Ideally, you should see a physio, straight away, but I know how long the wait for those are (unless you've got cash), so I'll tell you how I have rehabbed mine & you can see what you think.
Straight away you can do one move
The Finger walk
- find a wall then face it. Slowly walk your fingers up the wall until you get the first idea that pain is about to start, stop & walk them down (kind of like a front raise movement). Next turn sideways & walk the finger up, again until you are about to feel pain, then down again (a movement like a lateral raise). Until you get full range of motion (ROM) both ways, without pain, I'd stick to that. This will minimise the chances of you reducing your ROM because of scarring etc.
If you've got a separation, then chance are you'll need surgery to reattach, but if it's just impingement or other similar inflammed tissue, a partial separation, or (as can be the case in some of thses conditions) an arthritic complaint then exercise can be enough to recover. (for arthritis you'd need to start supplementing etc to try & aid recovery)
Assuming you've regained full ROM, next would be a series of exercises to strengthen the area:
Lying reverse flye
(thumbs up in the raised position)
30 degree lat raise
(If a lat raise out to the side is zero degrees & a front raise is 90 degrees then 30 degrees is just forward of a lat raise). Thumbs pointing slightly down in the raised position
Prone (or one arm) bent over row
"Press-up" off of a bench
Sit on a bench sideways with a dumbbell on each side. Grab the dumbbells & press them down on the bench, using your shoulder power push yourself off of the bench while still in the seated position, lift your bum off (that's the best I can describe that one...)
Push-up-on your knuckle
with palms pointing towards your feet (you may need padding for your knuckles)
You can also do L-flyes on a bench/standing etc. When you are stronger I've also found that strands (chest expander) is a useful move for strengthening the area.
I found MSM
seemed to help (cheapest I've found is from GNC) it's not capsules, but powder (works out cheaper that way)
( cheapest place I've found it http://www.healthspan.co.uk/
). Make sure it not shellfish!
was something else I tried that seemed to help.
You don't need any supplements, but I found they just helped get me better more quickly. I've got some ideas if it's an arthric condition, but these are just stuff I've known to work, no garantees on that one as some people do better, some not at all, if you need any advice e-mail me & I'll dig up some stuff for you to try.
Obviously plenty of water too.
If you've not got your condition diagnosed yet, go & do it. Lots of things can give you pain in the shoulder, from splinters of bone, to inflammed tendons or bursa. Any number of muscles can be the cause, you can even have bicep problems & get pain in the shoulder, so if you can, get it checked by someone who knows. It could also be a joint problem rather than impingement etc that may need treatment. Better to get it checked, if you can, just to be on the safe side.
Hope my meandering has been of some use to you