hi i got hit in the back of my head with a tennis ball pretty hard. male server. it made me lose vision (like when you blink your eyes) for a quick second. but i remember everything. didn t really hurt but it did take the wind off of me momentarily. i was fine but woke up with a little headache that lasted 30min. and now 5 hours later feeling a lttile dizzy. but not sure if it s because it didn t sleep too much. should i go to the emergency room??