Dizzy Spells When Standing

I've searched in the forum but about two weeks after surgery i started getting really dizzy like I'm going to pass out when I stand from a seated position. I'm fine standing from a lying down position. Getting my blood checked tomorrow but checking to see if anyone elae has experienced this or if it's not relative to the surgery. It's been 3 weeks of these dizzy Spells now.

Bilateral inguinal hernia robotic surgery with mesh