HELP fainting feeling even after eating?

Wondering if anyone has experienced feeling like they are going to bottom out or pass out all day long, even after eating. It's almost like I have low blood pressure or sugar. I'm nauseous and I don't feel good all day long. It's been happening since around the time of ovulation which was about the 4th and my period is due the 20th. Wondering if this could be associated w a BFP?