It's been a long time since you've posted. Anyway, I'll try to give some input.
All of your symptoms are very suggestive for a condition know as Chronic Fatigue Syndrome. Physical exercise, stress and cognitive exertions usually promote and exacerbate symptoms of this condition. Actually, is a systemic illness and you can experience many symptoms and they can vary from hour to hour. Severe headache is very common and you can feel it as a extreme pressure at the base of skull or behind the eyes and ears, also as a tension headache.
I need to note that in very rare cases some of the symptoms can be fatal.
I hope you've already seen some neurologist.
Please, write me back about your current condition.
All best to you!