What Causes Pain In Lower Ribs?

Hi my naim is Saso and I am 45 years old and I have pain in the lower left side under the ribs, I was in July for ultrasound but they did from the right side,my doctor after he had results told me that I am ok. I don't have any problem since couple days ago when I have pain on the left side ( appendex) but I don't have it because couple years ago they took out. This night just 30 minutes ago I fill strong pain on the left lower side under the ribs for about 20 seconds after that I still can fill the pain,it fills like a bruise so now I am concerned really. Thank you