Razor burn that won't go away

My hair doesn't grow back very fast or if it does grow back like right now, you can barely see it. I haven't shaved in a while- but I still have a LOT of razor burn scattered around my thighs and on the back of my legs. Why won't they go away? They're red and bumpy, almost like pimples. What should I do? my friends told me to use a loofah, to exfoliate the skin- but it doesn't seem to work. My razor burn hasn't vanished and I'm hopeless. Its it possible to get razor burn on the back of my arms? I've never shaved that area before- but there is also an INCREDIBLE amount of "razor" bumps on both the backs of my arms. It looks so gross because they sometimes turn really red and start spreading and other times it turns into my skin color- but the bumps are still visible. I've had them ever since I can remember. Is it genetic? Please help me however you can. Thank you SO much! =]