Tattoo Infection

I recently got a tattoo on December 27th on my lower arm. Seemed normal the first couple of days, because i got one before so i know the healing process, but like 3 days after it started to produce pimples around the tattoo which spread a little bit more to the upper part of my arm. I've been treating it with cortizone 10 because it itches too and that will usually start to heal it which it did a little. Its 9 days later now from when i got the tat, so should i begin to really worry, because they're still there. My tattoo artist told me to hold on before i got the tat so he could get ready to do it, and i figured thats when he put new needles in but i never physically saw him put the new ones in. Do my symptoms sound like anything serious because i'm starting to freak out?