What Causes Pain Under My Rib Cage?

i am having some pain in my lower left side like under my rib cage, I have been peeing a lot more but I have to force myself to pee I don't get the sensation that I have to pee ( ill feel a sharp pain in my left side and know it is time to pee),I've had the chills and sweats for about a day, I'm getting headaches and I have not been pooping normaly. What could I have?