What's very very low? Need a number. It's also not a good idea to self-diagnose. I can usually find 5-10 diseases that fits whatever ails me that day if I find myself browsing online long enough. Get a second opinion.
Also, blood pressure ranges can vary widely. Some people feel like they'll faint when they dip below 110/90 or something. Me, my normal bp is 90/60 and has been for years.
For the love of jebus stop taking the ephedra.