Ok, I'm still trying to figure out the difference between the always there muscle/joint pain and a muscle spasm. Does a muscle spasm knot up, then ache for several hrs and leave the place really sore for several days? I usually just have sharp shooting pains that leave me achy or just continuous aches. But, I do get something, right under my ribs that comes on fast and feels tight, hurts like heck and is sore for several days afterwards. Is this a muscle spasm?