What Causes Itchy And Sore Nipple?

Hey. I have had a problem with my left nipple for a few weeks now. It starts of with the nipple becoming itchy and sore, and moves to the outter part of the nipple. It than becomes red and sore and becomes I believe the word is inflamed. I have searched online and it comes up with breast cancer on most the sites I have searched, I havent been to my local gp as I am worried.