Don't Panic.
I understand how you feel. The same thing happened last year to me when yogi had his annual shots. I felt a bump on his back and immediately took him to the vet because I was afraid of what it might be. Especially since he was already three and this had never happened. The vet told me to wait and see if the bump went down because it was more than likely caused by his shots. I started to notice that it started getting smaller and eventually dissappeared.
