I have sinusitis and have the lightheadedness very frequently. My internist has tried Meclizine and Phenergen, two drugs that help curb symtpoms of motion sickness. My ENT said these won't help because my dizzies are caused from the lining of my sinuses being so thick that I have different air pressure in my head than outside my head. It's much worse when the weather is contantly in flux. It sounds crazy, but I have been tested for everything else. I also get horrible migraines with this sinusitis. Nothing has really helped, but I am now getting steroids injected into my sinuses, and I'm keeping my fingers crossed.

There are so many things that can cause lightheadedness, and we are all different. I think you are doing the right thing by getting tested, at least to rule out anything else.

Good luck, and I hope you feel better soon!