Extreme headache, feeling faint, eyc.

Lately I haven't been as hungry (I've never eaten much) so I started feeling weak. When I eat a little more than normal I get nausea, but never puke. I have had an extreme headache for over 3 days now, it's all my head that hurts and I can't lower it a bit or turn around. When I lay down on my bed, I have to sleep turning towards the right side because if I sleep turned towards the left side I feel like my head is about to burst and I cry from the pain. The only thing that stops it a bit is covering my ears really tight. I feel extremely weak and I always feel faint or lightheaded. Sometimes when I am standing up I start falling and any amount of exercise leaves me with a much greater headache, not to mention being unable to stand up.
What could be wrong with me?