I have this huge Long red mark on my thigh.. from me scratching I think.. I usually do get red marks when I scratch myself but this one looks different.. it's like dark red splotches of blood just behind the skin.. if that makes sense .. what does it mean? what's wrong with my skin? it looks scary.. it doesn't hurt or anything but it looks disgusting and it's pretty long and I know this red mark won't go away in 10 minutes like the usualy red marks I get.. help