Reinjured my strained back muscle yesterday playing on hard concrete ground in cold weather...?

As you know by now, your back and core is involved in almost anything you do. You have strained a muscle in your back and at this point this isn't much you can do other than put heat on it, whether it be a towel moistened in hot water or a cream or a heating pad. For the game you will most likely need a muscle relaxant prescribed by a doctor or perhaps you can purchase something at a drug store.