Suggest Treatment For Rib Cage Pain

Hi, Im 15 and for over a year I have been having serve pains on my left side just under my ribs and it spreads to my back, It hurts when I sneeze and Its not becasue of my period like my gma thinkks because i get the pain almost everyday. and b4 i started to get the pain i was awlays hot but since them im always cold, and I get fevers now. Could anything serious be wrong?