Lots of ice, on 20 min. off for 20. Take 600 mg. of advil/ibuprofen every 4-6 hours, WITH FOOD! it takes a minimum of 600 mg.s for it to work as an anti-inflammatory. Of course, if you have a sensitive stomach, or have ulcers, do not take it. And rest it, no heavy lifting, pulling with it, etc... for a few days.
I have torn, pulled, ripped, and over used more muscles and joints than I care to discuss, but this is the best advice the doctors ever give me.
If after all that, and it still not responding, then go to a doc and maybe have an MRI done of the shoulder.