I don't see a big problem with the pain that you've described. After every one of my outing I experience a little soreness in my shoulder and near my back. There is, however, a difference between soreness/discomfort and pain. If it is just sore after you pitch for a few days, I would tell you its just the result of pitching, which is a irregular motion for the body. If it's pain, that lasts a week or two, then I would have that checked out by a trainer. Know what your body normally feels after outings and be alert to any new areas that are sore after games.
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