I have nerve damage in my arm from an injury in 2020. I got my flu shot about 3 days ago in the same arm as the injury and my full arm is still very sore and swollen. Is that normal?

Hello,  it’s coming after a flu shot to have aches at the deltoid muscle and around the shoulder. This is most probably the reason for your soreness and swelling. It generally should resolve over a few days, so if it doesn’t then it might be good to get your symptoms evaluated at a clinic. Hope that helps!