Left nipple purplish?

I noticed a few months ago that my left nipple was a somewhat purple color and forgot about it for a while because I got busy but I've recently noticed it again. I've had issues with my left breast before. When I was 19 I started having random clear discharge. My breast was scanned and they found a mass that they said shouldn't cause any issues and that was that. I'm 21 now and have been breastfeeding/pumping for almost 10 months, the left is exclusively pumping because daughter prefers the right, but the purple happens regardless of whether I'm going to pump or have just recently pumped and is always there. There's no pain whatsoever in my nipple or breast and I've checked myself and I couldn't feel any odd lumps. I've added pictures and zoomed in as much as possible to keep much from being shown while also leaving the color difference obvious. Top is right, bottom is left. I will be making a doctor's appointment.