Hello, Get clinically examined by a GP, your symptom is indicative of not a pimple but rash over the tattoo. It is likely due to your skin that is very sensitive is rejecting the tattoo. Avoid bandaging or applying too much ointment. Do not let moisture get trapped under the skin. Excess moisture can cause pimples or rashes. Let the rash or blister dry out. Take care of your hygiene, make sure the area is kept clean. You can apply a thin layer of steroid cream to help it heal. Consult a GP, get evaluated. You may need to take a course of antibiotics. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K, General & Family Physician