I dont think it is possible to be able to get a concussion without being awoken from the impact. I think the most likely causation for the flare in your symptoms is likely anxiety from your belief that this event did occur. I would try to relax and think through the possibility of such an event causing a concussion and even more the possibility that it even happened in the first place. I know how hard it can be to deal with the obsessive thoughts that can arise from these situations. It can be impossible to not think about it, but I think the best thing you can do now is relax and try to be as logical as possible with the situation.

I also do not think it is even possible to be able to get a concussion from such a small force that would be transmitted accidentally from a small child.

I hope you feel better soon.