My costochondritis started during the night when I rolled over and felt a crack in my sternum. I could actually push my ribs and make them move.
This injury in the rib isnt there when I wake but comes when I steer my car, lift etc. I feel like I cant open my chest enough to stretch it out. Im taking anti inflammatories but they do fuck all. I do alot of stretching through the back and chest and this helps a little. I find that the body nurses a chest injury by "hunching".