Hi
Welcome to the MedHelp forum!
Chest pain aggravated by laughing yawning, moving in certain directions, stretching and deep breathing goes more in favor of costochondritis, which causes pain and tenderness at points where your ribs attach to your breastbone. The inflammation around the joint area gives sharp pain on taking a breath. This can also cause tenderness on pressing the area which pains. An orthopedic doctor can diagnose this for you. Generally there is no cause. However it can be due to infection, blow, injury, or fibromyalgia. It usually goes away on its own. Otherwise it can be treated with muscle relaxants, and non steroidal anti inflammatory drugs. It can also be muscle pull. Shingles can also start this way.
Take care!
The missing piece is the "etiology" - the root cause of the inflammation. This may be difficult to determine. The cause could be infection, either viral or bacterial, or be a result of trauma. The term costochondritis is not very helpful is telling you the cause of the problem. Usually it is self-limiting, although the time for it to go away may stretch into months. I had the problem years ago and it dribbled out to almost a year, only to go away and never again return.
It is what Londres said it is, it can be a very severally painful. I use to have it when I was in my 20's-30's. Get lots of rest and take some Ibuprophens. If its hurts for a while go see a doctor just for safety.
Costochondritis is an inflammation of the costal cartilage which connects each rib to the sternum. Uncomfortable but benign.