I Have An Unexplained Sharp Pain - Occuring Suddenly Maybe

I have an unexplained sharp pain - occuring suddenly maybe after I have been bending over working (I clean for a living). It is somewhere deep inside of me and feels like it's close to my heart - at times it feels worse the deeper breath I take. It also sort of feels like it is closer to my back now. just under my rib cage. Right now it's on the left side of my body. Has been hurting, like i said, off and on, for about 3 or 4 days now. What is going on? Why am I having these sharp pains. I have a pretty high pain tolerance and would not be at this site if I didn't feel like this is something I need to pay attention to. Kind of worries me.