Do I have neurological problem?

I have had constant headaches every day for the past 2 years or maybe even longer. I saw a doctor about this and concluded that they are stress headaches. I do think stress has a role in my severe headaches but was wondering what else could be wrong. My vision has gone from 20/20 to 20/40 to 20/50 and i am constantly nauseous and usually cant remember anything that has happened within the past couple of days. Recently I have had trouble sleeping, have had trouble breathing for nearly 8 years...had an inhaler but it never worked...sometimes have difficulties swallowing. I also don't eat very much. Something very light in the morning, at lunch and occasionally a good dinner ex. spaghetti. Do I have some kind of neurological disease or is it just a migraine?