I'm having a severe sharp pain under my left breast just over my lower ribcage. The pain is extremely sharp making breathing difficult. Applying pressure to it doesn't seem to help much. I also have a odd, numb sensation in my left shoulder which seems to be tied to this. Does anyone have a clue?
It is truly hard to say what it is without you being physically assessed by a professional. It may be a pulled muscle, but could it be something with your lungs or the breast itself or even something more. Sharp pain can be a sign of cardiac issues, as well, so any chest pain should be evaluated by a healthcare professional as soon as possible.
Whenever there is new pain of unknown cause it is best to be evaluated.
Here are some links you might find helpful as you're dealing with this issue:
Heart Attack Symptoms in Women
Heart Attack Symptoms and Warning Signs