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The most likely cause is 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.
If this does not help then gastritis, acidity, gastric ulcer and pancreatitis will have to be ruled out. Take care!
I think reflux or heartburn but you should make an appointment with your doctor to discuss it.
First are you a female? IF so my next question is are you pregnant? If you are pregnant than this pain is due to your enlarging uterus. As you uterus grows it pushes all organs to an upward motion and many women including myself unfortunately go through. Second it could be acid rfulx or gas. If you are not pregnant I would suggest you take some zantac that you can buy from any grocery or helath store and it works wonders for that.
It prob is wind or indigeston, have you tried senekot works for me.