Busy bees tend to be too busy for their own good -responsibilities, endless to-do lists, mental stress, and THAT another phone call.
You will never believe this, but overthinking causes headaches in the form of tension headaches. Also, headaches that feel like empty-headed when you cannot just think or remember anything. It means you used up all the reservoir energy and substances for the brain; therefore headaches.
I know it's super difficult, but you just need some rest.