Something hurts on the left side of my belly, under the ribs exactly ??

Hi everyone, here is my story, the first time I felt it it was about 3 years ago, and I didnt pay much attention to it cuz it didnt really hurt that much, and I thought it's gonna go, but once in a while i feel same thing over there, and what happens is a little bit of pain and i can feel and see that side is pulled inside my body, it usually happens when im hungry and need food, or when im so tired need to sleep. now im having it more even when im not hungry or sleepy, the spot that hurts me is on the outside area of my abdominals, on my left side, just bellow my ribs. The first time I felt the pain I tought for sure it was my heart, so next day I played soccer and run a lot, so I know it's not my heart, but something else, and im wondering if it's gonna affect the heart or i dont know, please let me know, Doctor is too expenive