What Causes Severe Upper Left Abdominal Pain?

Hi, my name is Andy, I am 23 years old. Since early August, I have been experiencing throbbing abdominal pain. It has been in several areas, but primarily on my left side, directly below my rib cage. Its a throbbing achiness. on a 10 scale, I would say it s about a 3 or 4. Not super painful, but just enough to make me uncomfortable. It seems to be made worse when sitting for long periods, and sometimes when I m walking as I raise my leg. About two weeks after it started, it seemed to be disappearing, but it has become worse in recent days. It seems to be worse when I am experiencing emotional stress. Today, it has been particularly intense. I took pepto about 30 mins ago, and it seems to be improving, but I am seriously considering going to a clinic. My family has a history of abdominal and digestive issues like IBS. Any advice?