Nipple discoloration?

mama.jinx • Wife // mama // coffee snob // Gemini
I've had my nipples pierced for a few months and they haven't given me a lot of problems. 
I'm getting another keloid on my right one and it stings. When looking at it I noticed both my nipples have a purple spot on the bottom.. It's really worrying me and I need answers. Anyone know what's going on?