Does anyone experience the sensation that the back and sides of the brain are swollen when they work on math puzzles, read, play videogames, or do anything visually demanding for a long period of time. I don't seem to experience the same sensation when doing auditory based tasks. However, that sort of stimuli still affects me.

It almost feels like a low-grade headache with subtle dizziness. I also feel the urge to eat or drink, even if I just had lunch.

My family members claim that they never experience any physical sensations when doing the activities I talked about, and they say they could do them for hours on end. The only thing stoping them is boredom.

This is something I've experienced my entire life and assumed it was normal. However, it started to get much worse overtime. Eventually I was diagnosed with a cerebellar brain tumor. Maybe my compromised visual-spacial system gets fatigued very easily. I'm not sure.

I struggled mightily in math and I think this is one of the reasons why. All the numbers and formulas were just too visually demanding for me.

This sounds like a question for a Neuro Rehab specialist. Did you have neuro rehab after your surgery ?

You might need to avoid doing those tasks for long periods of time. Take breaks.