Your increase in symptoms are NOT from an accumulation of head bumps. That question has been asked and answered over and over.

You need to learn to gauge your activity. There is no formula of 2 hours activity, 30 minutes rest. Each activity has its own stress level. If you notice a spacy feeling, stop and take a break. If you are reading and need to reread a line, stop and take a break.

I believe your struggles are from how you deal with stress and possibly increase stress by trying to understand every little symptom. You need to get your anxiety under control.

There are NO worthwhile answers to your why questions. Over time, you might start to notice trends. 2 hours of reading could set you back. Or, participating in a multi-person conversation may cause a crash. Only you can connect the dots. Find something simple to occupy your mind with.

You need to find some somewhat sedentary activities. What would you be doing if you broke you leg badly and needed to be sedentary for a month ?

Learn to play a musical instrument like the guitar or something. Learning to play guitar chords and pick at the strings could occupy lots of time. Or. learn to tie fishing flies. There are lots of activities that are just manual based with no need to be out and about.