Hi, about three years ago I found a clear bump on the outside of my thigh and accidentally scratched it. It became very red and slowly began to resemble a blood blister. Over the next few years it has turned from red to purple and black - especially in the past few months - and has increased in width and thickness. It is smaller than the back of a pencil and about 1 mm thick. I am 15 years old and after reading about nodular melanomas I am really worried.