About a week ago I found a pimple right under my right nipple. In the summer I do tend to get pimples in that area as I have bigger breasts & well...they sweat.

I let it be, but it still looks the same. I it's red right in the middle & not that big. I'm only 20 so I feel like I'm too young but I just want to be sure. I attached some pics (sorry if it's blurry). It doesn't hurt to the touch, but if I really go at it, it does. What do I do? I'm thinking it's just a pimple.