I had similar symptoms for a few weeks...turned out to be a sinus infection! No runny nose or anything...just headaches, dizziness, feeling tired, etc.
Hope they find out and get you well!
Turns out luckily to have just been an incorrect refill of a blood pressure med! Was twice the strength it should have been, whoo doggie fun times. I will always inspect the pills now at every refill! Learned my lesson!
Finally getting to post office tomorrow morning via my friend. The vertigo should wear off soon but I'm not going to chance it, will use the Friend Taxi and make sure I get to the post office!