What is this sharp pain above my left breast when breathing in?

What could cause this pain in my left breast?

• It just started last night.it's like a grabbing,stinging,or even gnawing pain in my left breast.it's been going on since I woke up too. My dad thinks I may have pulled a muscle but I'm not sure... I don't think it's a sign of a heart attack because heart is beating very steady and my breathing is fine...plus I'm not dead yet. I'm a 20 year old female Ifthat helps any. No history of breast cancer in my family either.

• Answer:

  Have you felt your breast where the pain is? It could be a cyst. It just feels sensitive and is a little harder than the rest of your breast tissue. It could also just be the way you slept-- like if you slept on your stomach. I'd wait a few days to see if it goes away.. if it doesn't then you should see your doctor because it's the only way of knowing for sure.