The Other Night While We Were Driving Home At About

The other night while we were driving home at about 65 miles per hour, we had to stop almost immediately due to an elk standing in the road. Starting the next day, I've had concussion symptoms (headache/dizziness/fatigue/sleepiness/mental fatigue/brain fog/difficulty concentrating/feeling out of it). I did not hit my head, but I did sort of brace it/try to hold it in place while we stopped. Is it possible to get a concussion just from slamming on the brakes at 65 miles per hour?