What Causes Bumps On Arm After Being Tattooed?

Hi, I recently got a tattoo, 9 days ago to be exact, and the past few days I have developed pimple-like bumps on my arm where the tattoo was done. There aren t any bumps on the tattoo, just a few around one spot, and the rest of the bumps are throughout my forearm. I m not sure what this could be?