7 week old baby keeps crying...help!

My nephew got his first injections today and he keeps crying non-stop, to the point where his face is red. I feel sorry for him. This is my sisters first child and she's stressed out and is crying too. My mom tried humming to baby and rocking him but he isn't calming down....please any advice will help. Thank you☺ Update: Baby is all well now, thanks for the advice ladies, really helpful!