Help something’s off

Okay something is wrong. Like seriously. For some reason I keep getting these dizzy spells that comes with fatigue and nausea while making me feel weak. My head will then get hot like this feeling that I’m not get any blood circulation in my brain. Doesn’t happen everyday but some mornings at work and i can’t sit down at work so I have to make up an excuse like using the bathroom just so I can sit for a few minutes to try and calm the spell down. It sometimes help but sitting for only 5 ish minutes doesn’t help much when this feeling is lasting at least 30 minutes. Has anyone ever had this before and did it solve itself. Currently almost 17 weeks.