Why am I always hungry?

It seems as if I am always hungry. I eat enough though. But when I eat, an hour later I'll feel hungry, but I can manage not to eat anything. Then 3 hours later, I am really hungry and need to eat. 5 hours later I am starving and I feel sick, dizzy, hallow, I ache, I may get a nagging pain somewhere, like my arm, hand or foot for example, my mouth feels watery and spongy and I'm so drained and I get a hunger headache or something...I don't know if this is normal, but I don't think it is. It's exhausting....