I suppose the first question most would ask.... is there any chance of being pregnant?
I recently had bouts of awful nausea off and on and it ended up being elevated blood pressure.
In your situation you have some other symptoms which could be linked to the nausea and definitely aren't linked to blood pressure. Are you on any particular meds? My cousin had a viral infection and was popping way too many pain killers with codein in them and it ended up constipating her and giving her lower back pain. They had to admit her to the hospital. She never even realise she was that constipated. Once they gave her an enema and everything came out she was fine. She never mentioned having nausea though. Your situation sounds as if you have a lot more going on. If i were you i wouldn't be holding off seeing a doctor. What you have could be one thing or could be a couple of things. I'm sure the nausea is linked to one of them.
Go see a doctor, even if you don't like doctors. You could do more damage to yourself waiting around on here for someone to reply. Hope you feel better soon