I think arm pain because of an injury is very common. It's always a good idea to think about whether a new kind of movement or exercise was done recently.
I started a new type of exercise using the arms last week. I must have done something wrong with my left arm during the exercise because it started paining. Initially, I couldn't understand why it hurt. Then I realized that it must be the new exercise. I stopped the exercise for a few days and rested and the pain went away.