What To Do For The Severe Sharp Pain In The Upper Left Quadrant Under Rib Cage?

Hi. I m a 35 yr old male. Went to the ER yesterday with upper left quadrant pain. CAT scan was supposedly clean and my blood work showed 13.1 WBC and all else was WNL including pancreatic enzymes. Today I woke up with severe sharp pain in the upper left quadrant right under my rib cage. I couldn t even stand up straight and it radiated up to by left trapezius. I just tried to have some dinner and the pain became burning in the pit of my stomach and the sharp pain under my left ribs got more severe. I am also running a 99.8 fever currently. What could this be?