Considering that the 'L' key and the 'I' key are somewhat close to each other, I'm guessing that the OP meant to say "URI". Honestly, I've only seen these bumps one other time, and as your vet suggested it turned out to be a slight reaction to the medication. Doing a little bit of research on the medication, it seems that a common reaction to ceftazidime is swelling at, around, and near the injection site.
Hope Ivory gets better soon, he's beautiful.
-Fataltix