Dull pain in middle of butt cheek on left side. pain when sitting but better when moving. muscle? anything i can do or take to relieve the pain?

Probably back: Back pain often radiates to the buttocks and is often worse with sitting (which stretches irritated nerve fibers from your spine). Tylenol (acetaminophen) and ibuprofen can be used, but the results are often less than satisfactory. How long have you had it? If longer than two weeks, see you doc. If you have fever, weakness, loss of bowel/bladder control, difficulty walking or intractable pain go to the ED