For about the past year I've been getting headaches and extreme exhaustion almost daily. It happened more during the school year usually during my last class, right after school, or sometimes in the evening, but it would always last until I went ot bed. It made it hard to do any of my work. The headache was usually on one side and was never really severe, but I always felt tired and unergetic. It's happened a few times this summer...it's happening right now in fact. My brain seems slower when I' get like this too.
I have no idea if it's related, but the past few days I've had a hard time getting to sleep, and I've woken up really tired.
Whenever your body is in pain get it check out by a doctor. There are many reasons why you could be having headaches and it could just be stress. However, we don't know that unless an MRI is done. Headaches can be from sinus issues or even allergies. I would advise you to get it checked by a neurologist. Feel better soon!