Even at slow speed, coming to a sudden stop can send your brain bouncing against your cranium. I know how doing even small things (even a big sneeze), can flair existing symptoms. That can make it hard to tell if you've just suffered a new concussion.

You might want to check yourself for some of the most common symptoms. You've already got some (like stomach upset), but are your pupils even and can you walk heel to toe? Have a friend check that you can track objects with your eyes. Assuming you could do it before, can you still count backwards by threes? If you have any doubt at all, I second the advice to seek medical help.

I'm sorry about your car and I hope this doesn't set back your recovery.

Take Care