it's not that bad, it just feels like you've been punched in the arm. move it around and work the muscle. it goes away in a couple days

It won't last long. You'll be fine.

Don’t avoid using the sore arm. The more you use it, the better. I know it sounds counterintuitive but it’s true. My arm hurt sooooooooo fucking bad after the first shot, and I laid in bed most of the day and just sitting up was excruciating agony. Finally I forced myself to get up and do things and it helped a lot. Dishes and shit. Driving. Whatever anything. It all helped. I couldn’t raise my arm above my head, but doing all the motions I could do really helped. Something about working the muscle to stretch out the soreness idk. But it’s what they (the CDC etc) recommend - keep it active. And I can tell you anecdotally that it definitely does make a difference. Good luck to you both.

Why doing anything?

Toughen up, get over it.

Tylenol is amazing at getting rid of the pain. And your dad should've helped.