Did you read the whole thread? One of the people was diagnosed with Sarcoid granulomas.
I'm NOT a doctor, but my first thought is over moisturized. I'd try rubbing alcohol for a few days. If you're really worried, go see a doctor.
i got my tattoo while down range in Afghanistan by a fellow soldier conditions its Afghanistan so yea less then desirable but he did everything a shop would have done back in the states just in a room we built with a lot of dirt and god knows what else but i occasionally get the same bump as u @jessicaRae all my tats are black as well tbh i want to believe its just the way the artists put it on the skin maybe went to hard or a weird angle or who knows what but i noticed everyone having this issue is with all black ink tats and only think i can think is it has to be the way the artists used the gun on our skin or else everyone in the world would have issues with their all black tats right? the bumps come and go a little painful to the touch like pimple or ingrown hair about to burst you know sorry no pics phones dead but if your really concerned get it looked at by a medical professional take care