Fainting?

Kayla • 22! married to the love of my life! Love photography and nature.
Anyone else around 20 weeks, who did their normal thing all of a sudden feel like they were about to faint? 
I was clinging to my patients restroom wall when I felt like I was going to faint, thankfully I didn't freak my patient out because she was asleep. My blood sugar was 110 and my BP was 130/79 so everything was okay. Just wondering if anyone else was like this and why?