Low blood pressure

Has or is anyone suffering from low blood pressure in there pregnancy and experiencing dizzy spells and headaches? ? I been to the doctor multiple times but they cant do anything for me as they cant prescribe me anything to get it up and has left it in my hands to get it up but its not working and im over feeling like fainting all the time.. i struggle to do the house work and run around after my little girl please help im 12 weeks and 3 days with my second