Symptoms

For the last couple days, random times, I have been very lightheaded and sometime seeing spots when I blink. It's worse If I'm active at all...even walking through the grocery store, I have to stop and catch my breath or sit down bc I see spots and feel like passing out. Ive checked my BP and even my sugar just in case and both were fine. Has anyone else had these symptoms before? I'm 32 weeks. Next dr appt is Wednesday so I'll definitely be mentioning all this to him, just curious of anyone else has had this happen? And what it could be?