Hello, I can understand your concern for red bumps over your tattoo. After reading your query I can make out that you have got contact allergy to the dye of the tattoo. Though it is quite a long time since the tattoo is been made but in some cases it can cause delayed allergy. I suggest you to show your tattoo to a dermatologist so that a proper care could be given to the area without spot formation. In my patients I generally use a cream containing clobetasol or Mometasone for immediate help. If required I give oral steroids and antihistamine such as cetrizine for two times to reduce the allergic phenomenon. I hope the above information will help. All the best.