i get that too! i'm not quite sure what it is, but i think it may be hives, which i get on a regular basis... also, it could be from shaving too, like really nasty razor burn. try getting some Gold Bond anti itch powder, like the super strength stuff, and apply that every time you get itchy. just do all you can to not itch, so they can heal as fast as possible... and try not shaving there for a while to see if that's the cause. good luck!
Make a doctor's appointment to have it looked at. It could be a heat rash, infection, or other irritation, but only your doctor can diagnose you. I hope it goes well. Take care.