Can you lift you arm above shoulder level? If you can't, it is very likely that you did tear your rotator cuff.

If you can, I'm betting it's a separated shoulder ( damaged ligament between shoulder blade and collar bone). I've separated my shoulder before and your only real option is likely physical therapy as most surgeons won't operate for this (too risky, many arteries located in shoulder).

It's probably a good idea to get yourself a sling to keep your arm in right now, as it could prevent further damage in either case. Then, get it checked out by someone who's qualified and go from there.