Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to obtain a history from you and examine you, I cannot comment on a formal diagnosis or treatment plan for your symptoms. However, I will try to provide you with some information regarding this matter.
A normal sleep study/EEGl during this episodelikely rules out seizures. You mention that you have this feeling, which is followed by a severe headache. These feelings really may just be an aura to your headaches, usually migraines.
In treating these such as in yourself, the treatment should include two types of medications: preventative therapy and abortive therapy. Preventative therapy is a medication that would be taken every day regardless of whether or not a headache is prevent. This type of medication is used to prevent headaches from occurring, and there are several types including but not limited to beta blockers such as propranolol, calcium channel blockers such as verapamil, and others including topamax, depakote, elavil, etc. A lot of these medications were invented for other uses and are used not only for headache but also epilepsy and depression. They have proven very effective in preventing headaches. You may want to discuss whether your medication dosage needs to be adjusted.
The second medication is abortive, meaning it is used when a headache is coming on. The medication used depends on the nature of a headache. If it is a migraine type headache, a group of medications called triptans can be used. And so on. However, with frequent use of abortive medications including triptans, tylenol, advil, and others, medication overuse headache occurs. This requires a specific treatment in which the over-used medications are slowly stopped and replaced with more long-acting medications. Tylenol with caffiene, and similar medications, can cause medication overuse headache if used too frequently. Lyrica, which is used for fibromyalgia, can be used for chronic headaches too.
In addition to all these, lifestyle and dietary modifications need to be made. These include exercising and avoiding certain foods that are prone to triggering migraines, such as chocolate, aged cheese, caffeine, MSG (usually in Chinese foods), Doritos.
I would recommend keeping a diary about possible triggers to these episodes.
I hope this information was helpful.