What Causes Constant Pain Below The Left Breast?

Hi Dr, I have a constant pain below my left breast, it s worse when I exercise I had this pain for more than 6months, initially when it started I felt it on my right side and it was only for 2weeks .i have done chest ctscan and nothing was found And also I get this attacks in the center of my lower abdomen the pain sometimes comes from the left side it s so severe that I can t even move , now when I have sex I feel severe pain after intercourse and the pain goes to the lower back and rectum and I have been to the Dr and they did an abdomen scan and nothing was found