Almost passing out?

Kins
I will call my doctor, her line is busy right now.
I was walking around target for a little bit. I went to checkout and I got really hot, body was going numb, and my hearing got really muffled. I felt my face change color I think lol Luckely the Starbucks right by the checkout line had seats so I could sit down. I'm currently still sitting...not sure if I should drive or not? 
I'm a FTM at 31 weeks. I've heard this is normal but wanted some input? I've had  water today, too. 
Thank you!