This is gonna sound weird. 3 days ago I had what felt like a small muscle cramp, mid back, left side. It never spasmd or fully knotted into a severe cramp. It also would never release or go away. No position of movement or stretching caused any change in the dull small knot in my back for 3 days. 3 or 4 tylenol might allow enough relief to fall asleep. Yesterday morning I awoke to the pain being gone mostly and I thought Great! Not so fast. Now left side at bottom of rib cage in front, my chest, has the knot almost like it moved. Also now causing my skin to feel overly sensetive kinda sore over the affected area