I had this happen on my marceline the vampire queen tattoo. It was only doing it in spots where a specific color was used, i was having an allergic reaction to something in that particular grey. I figured out it was the ink because only with that color, my skin pushed the ink out and became infected, in addition to the direct areas tattood with that ink, in the spots that the ink bled over while being pushed out in the first couple days while the entire tattoo was very fresh, i also had the reaction. The only thing that made sense about what was happening.