What Causes Soreness And Swelling Of One Nipple And Montgomery Glands?

One of my nipples and areola are extremely sore, swollen, red and bruised looking, warm and hard (like a lump that is slightly larger then my areola). I have never been pregnant. It appears to have grown in double the size since I first spotted it about a week ago and it hurts all the time, regardless if it is being touched. What could it be and what is likely to happen?