muscle spasm
"I have severe neck pain and muscle knots in my neck.  I've been told by my doctor these knots are essentially small bone spurs that protrude into the muscle tissue which causes spasms.  This is particularly bad when its damp or rainy.  I was prescribed 10 mg of Flexeril.  Overall, I'd say it works great with very few side effects.  The only issue is some days 10mg doesn't seem to help very much.  I have taken up to 15 mg (one-and-a-half) when the pain or knots are really bad.  At the 10 mg dose I do NOT have any problems with being sleepy and take it during the work day all the time with no sleepiness.  If I take it with a pain medicine it will make me drowsy. The sleepiness side effect seems to vary person to person."