Have you had any blood tests done? Honestly, I wouldn't suggest taking random iron supplements unless you need them. Excess iron can cause as many problems. Do you drink beverages other than water during the day? They count too.
If you haven't had any blood tests, then I suggest getting a CBC, iron panel (ferritin, serum iron, IBC, and iron saturation), and a full nutritional panel (vits/mins) done. Low blood pressure can also indicate a thyroid or an adrenal problem, so it would probably be good to talk to your dr about this.
Good luck and please keep us posted.