I was running and I hit the middle of my

Patient: I was running and I hit the middle of my back on steel (it was bleachers, I’m clumsy, sorry) and it hurt like hell, but then after the pain and the soreness, I realized I had a small bump and in a matter of two or three days I had a huge lump, I can only describe it as semi hard, it protruded out like the size of a lemon. It was directly aligned with my spine. Also, this happened when I was like 10 and now I’m turning 20, but when I went to the doctors to get my weird lump checked out they said it was nothing so… yeah I really wanted to know if it really was nothing or if past me had something to be worried about. This may sound like a joke, but I really want to know what might of happend, thanks in advance for helping out.

Symptoms: Soreness, pain, lump