I'm no expert, but in my research I've learned that there's a few possible causes for this. If it's an allergic reaction it can go away on its own. Some get it days after getting the tattoo and others years - it varies person to person. If it doesn't go away on its own definitely go see a dermatologist or at the very least talk to your tattoo artist.
It could also be an infection caused by lack of proper care during the healing process. I've also learned that applying too much skin care products can essentially cause itchy, white bumps.
Again, I'm not an expert and someone else here will probably have a better answer for you. But if you're that worried about it talk to your artist or see a dermatologist. Good luck and try not to worry.