Sodium contributes to high blood pressure - so if you already had low blood pressure and you cut out salt it may be causing the lightheadedness - BUT still get it checked out ASAP
I wouldn't advise increasing your salt either. It's too easy to go overboard and raise your plood pressure too much which wouldn't be good either.
Make sure you are drinking a lot of water, to make sure you are not dehydrated. Make sure you have a mixed protien/carb snack (celery & LC cheese) or meal every 3 hours to keep your blood sugar level.
Do you have a cold? Ear ache? Maybe it is an ear problem like mine.
Do what you have to do, but get to the Dr ASAP - your health is not something you want to mess with and since none of us are Drs (that I know of) please check it out to rule out anything serious.
How long has this been going on?
I had vertigo for 2.5 days and imagined I was dying of a brain tumor

- I can't imagine having it longer! I couldn't walk without feeling like I was going to tip over.
Get better.
Kim