Ay, first time mom ka rin! Please check with your baby's doctor agad, ha, even just a quick call to the clinic to describe the bump, para ma-ease your mind. One of my mum friends had something similar after vaccination and ang doctor lang talaga ang makakapagsabi kung normal lang or kailangan ng follow-up. Don't worry, madalas okay lang yan, pero better safe than sorry with our babies! Kaya mo yan, mommy!