I have a huge lump/bruise on my leg?!

So I was messing around today and pretended to fall over at school today but in doing so I slid into an outward corner of the wall. I was running kinda but when it happened I felt like a burning sensation on my leg and it hurt a little but I just kind of ignored it. When I got back to class I lifted my pants to discover a giant baseball sized lump on that spot. It started to hurt more as time when on when I walked but not too bad and when I checked again there was this black bruise the size of a golfball on the center. It hurts too touch and sometimes when I walk. Is it serious? I Iced it for 2 hours with no real results and I'm about to take a shower in Epsom salt. Should I be worried or is it just a bruise and it'll go away on it's own? By the way I'm 17 and the lump rises a few centimeters above my skin and is extremely noticeable. I just want to know if I should be worried.