What would cause major headaches and sleepiness?

Several things: Headaches have many causes. See the list on the picture. I suggest you see your physician and discuss a plan to determine the cause. Your doctor might order imaging of brain and optic nerve exam to rule out serious conditions.

One possibility...: Especially if the headache is worse in the early morning, consider being evaluated for obstructive sleep apnea. This disease, which disrupts breathing and sleep, can often cause a combination of headache and excessive daytime sleepiness. Your pcp or a neurologist can help decide if a sleep study is indicated.

Morning headaches: Headaches on awakening and daytime sleepiness are two common symptoms of obstructive sleep apnea syndrome.