this could be related to your ear,it can make you go off balance and dizzy,the headaches sounds alot like pressure headaches which could be down to the stress of your thoughts,i suggest you take another trip to your doctors you may need another course of treatment,i wouldnt worry about strokes and other things it just adds to your symptoms.
most likely inner ear that controls balance and can make you very dizzy ... which can cause headaches... i would get it checked just in case ... better safe then srry dont wait to long cause if it is something serious they could catch it in time... if you experiance nosebleeds during these "spells" go to the er asap... could be nothing at all dont stress too bad makes it worse ... could be a pinched blood vessel easily fixed
I think you should go to the doctor and tell him/her what's going on if you haven't yet.