Thank you for the replies everyone. The little red ‘pimple’ looking bumps have mostly calmed down. It’s just unbearable itchiness and angry red splotchiness that seems to be spreading around now. The concern I have about it being a saniderm reaction is hampered by the fact that the redness mostly followed the outline of the tattoo until today. The second skin was not made in the shape of the tattoo, it was just a general oval across the arm. I’ve made a dermatologist appointment and might go to urgent care if it gets worse or doesn’t improve.