Little one got vaccinated :(( keeps crying

Help me out please.

So I got my gallbladder removed laparoscopically 5 days back and got my little one (almost 8 weeks old) vaccinated today. He got 2 shots, each in one thigh. One of them was all swollen and he kept crying. I put on cool gel patch on that thigh and have been giving him panadol 6 hourly. He isn’t feeding well. His wet diapers have decreased. Although he did poop. When I got my gallbladder removed we had to shift him all to formula feel from exclusive breastfeeding. Now my milk supply has tanked and he still hasn’t adjusted to the formula milk. How much time do these injection site hurt? Is he going to be fussy for a long time? I’m so worried. My mama is taking care of him and I feel like a failure.