I Was Hit On The Back Of My Neck Earlier

I was hit on the back of my neck earlier today with a medicine ball, and then right after, another medicine ball bounced off the top of my head. Within a half hour, if I held my hand at a certain angle (also when holding my phone to text while laying down), my hand shakes/trembles somewhat violently. I had a headache right away, but it had seemed to subside with busy activities. However, the headache has returned (but advil seems to help).