I don't even try to classify the hit as a concussion or not. It is a losing game. It's a bump to the head. They happen. The anxiety of trying to classify the bump is just as damaging. Worrying about the future is also a losing battle.

Your nausea can be due to the anxiety or a vestibular issue or ?????

I've been dealing with this issue/risk for 40 years. Try to just take some reasonable precautions and go on with your life.