Decades ago when we were young at school we used to knock each other out. First time I saw it I thought it was fake, until I had it done to me. You had a memory lapse after this that varied between people, of momentary to whole morning. We never realised how dangerous this was until (in a different school) there was a lasting repercussion and a warning came out about it. I don't want to go into the method because of the danger, but it is a similar effect to what happens in shallow water blackout during diving. This could be replicated kiting, by exertion (oxygen intake) then hitting (compressing) your chest. Sure your doctor would have considered it.
You may be incredibly lucky that you weren't driving and had an accident. Imagine trying to explain it in court. Hope iit all turns out ok
