That's called neurofatigue and it's a sign of inflammation. Inflammation is what causes the symptoms.

A lot of the foods we eat cause inflammation which inhibits the healing, so avoid processed foods, fried foods, fast food, sugary drinks, refined carbs, and processed vegetable/seed oils. Eat a high-fat, low-carb diet.

Lower your activity to a comfortable level to avoid the overstimulation, then gradually increase your activity level.