Hello, Since Last Year (2014 Currently 2015) I Have Noticed

Hello, Since last year (2014 currently 2015) I have noticed a lump on my right tesicle. The where abouts of this lump is right ontop of my epidermis meaning that my epidermis is swelled up or enlarged for an unknown reason and when check my left tesicle there is no lump/Epidermis swelling. All ai can recall is being kneed in my crotch back in 2014 fairly hard by one of my class mates. I'm a 14 year old that needs help. I know for a fact it's not cancer because I got my physical last month and there was no signs of ANY cancer any where on my testicles other than that problem with my epidermis! PLEASE HELP!