Your brain's tolerance for a concussion does not reduce by over-doing it. Your tolerance for a triggering event is reduced by lack of sleep, fatigue, and all of the overdoing it issues.

This was at most a relapse, sort of like bumping a pre-existing bruise. It does not need to cause injury to cause symptoms.

From what you say, it appears you are hyper-aware of any symptoms. This is not good. You need to learn to ignore minor symptoms. Or, at the least, acknowledge the minor symptoms and just move on.

Your mind may also have a ready to go set of memorized symptoms to play back when a startle or other non-concussive trigger happens. These are like PTSD flashbacks. Try to recognize them as flashbacks and move on.

I routinely have balance issues, sort of a light headed balance issue. I just stop, regain my balance and clear head and go on. I play ping pong and routinely have to stop after leaning over to pick up a ball. I just stand up, grab the corner of the table and wait until my brain is ready to return to action. I don't dwell on it.

So, learning to move forward despite symptoms that come and go will be to your advantage.

My best to you.