+1 on the ICE.
About 6 months ago, I was reaching for a stray sock at the back of a clothes dryer, and hyperextended my left shoulder. It was sore as hell for a few days, and when I tried to raise my arm more than 90 degress it was really painful - sooo, I started using my right arm more instead. I finally went to see a doc about 6 weeks later and found that I had adhesive capsulitis, (aka "frozen shoulder), on the left side. The good news was that there wasn't a tear of the rotator cuff or surrounding ligaments - the bad news is that its taken about 2 months of PT to regain about half the range of motion I had before the dryer mishap.
Fortunately, I was able to continue riding my dailiy 16 mile round trip to work without incident. Long story short, if it doesn't feel better within a few days, its probably better to see your doctor sooner rather than later. Take it easy, get some rest, and feel better soon!!