I tore my rotator cuff 21 years ago when I was 14. It was a slight tear and I did PT and just stopped playing baseball. It still hurts if I sleep wrong, throw a ball for too long...odd weather makes it ache. Also if I fall while boarding it hurts. I would get it looked at if possible, but also do not push it as you can do more damage in the long run. You want it to heal for sure....
Likewise on the rotary cuff. I fucked mine up two years ago. A MINOR tear. Went to PT. Honey gave me some weight training excercises to do. I snowboard, skateboard, and play softball, (tackle) football, and am a huge billiard junkie. If I do *any* of those for several days in row, for extended periods of time, my shoulder hurts. Playing pool is actually the worst of them all. If I sleep wrong it hurts. If I stop doing the weight training excercises, it starts to hurt more. I will have to do those the rest of my life. My shoulder is never going to be same again. I am aware of that, and just have to alter my life in order to deal with that truth the best that I can. And my other arm? That one has a metal-rod in it from a motorcycle wreck. I'm lucky to be alive, let alone having 98% use of that arm. Despite a compound fracture, and metal rod that is imbeded in my bone for the rest of my life, the tiny little tear in my rotary cuff on the other arm causes more pain, and more problems than the "serious" injury in the other arm that has a metal rod in it. Irony runs thick sometimes.
Anyway, the point in all this personal digretion is that an over-all small injury can really fuck-up your shoulder up, and your life. Without know WHAT to do in order to make it better (i.e. proper PT), you can make the injury worse. You can also lose a lot of use of your arm. I am not trying to scare you, I am just trying to be real with you. I have a long and sorid history of fucking myself up (inc. shoulders) from all kinds of sports. I not only know what can happen, I've *had* it happen.
Put ice on it. Get a sling from the drug store and wear it, all the time. Even to bed. Do not move your arm at all. Take IBUPROFINE, as it is an anti-infalmitory. 4 pills is usually a subscription sized dose (800mg, I think). If there is not a SUBSTANTIAL difference in your arm in 5-7 days, start researching free clincs. Call a local hospital and tell them your situation. Check out local med schools, they often let students (under supervision) do work for free. Do your homework. Use of your arm might depend on it.