I get that too, often actually, because I've had muscle problems since I was 12. If it's the same thing, then you have two options - firstly wait, because it does go away after a long and annoying while. Secondly (and much better) go to a Physio and tell them, they'll do a sweet deep tissue massage or trigger point therapy and do whatever they tell you to do (exercises, take it easy, or whatever) it should get better after that.