rash on boob

i've had pain that feels like a hot iron touching my breast from my neck bone to my breast for about 6 months now, it's a little more red in color than the other breast, a bit bigger. i've had a rash on it for a while, i feel around sometimes and feel little hard knots, but they are so small it's hard to find sometimes, underneath my boob, is like little pimples everywhere, but on the side of my boob a new rash is appearing. should i get looked at.