Any time my head is under the influence of a certain force, i start to feel extremely tired, right after eating something.

It happened after a light bump of my head, after a bump of my body, that resulted in a fast head movement, after driving, after jumping, after running.

The tired feeling lasts for a different time frame. Sometimes I feel fine the next day, sometimes it takes over a week until this extreme tiredness goes away.

Does anyone know where his is coming from? Has anyone experienced it on his own?

It is surely not just because of the blood sugar. It happens only after a bump.

Maybe it's something in your neck ? There can be subtle neck injury and inflammation going on at C1, C2 in your upper neck. Have you got it checked ? This is alter the blood flow to the head I think and can cause symptoms . others will be here to offer a better explaination and help.good luck