Almost passing out during pregnancy

Ladies, I am wondering if I should call my doctor about what happened today at work. I work retail, and I'm a cashier and it's been so busy during the holidays. While I was working, I started getting really dizzy, and then I started to lose my vision and hearing and got really hot. I was so close to throwing up. After a little bit, I had the strength to go in the back and rest. I felt fine after that, and I was freezing. I'm doing ok now but I was wondering if  I should worry or not. I ate something before I went to work, and was drinking plenty of fluids. I'm 13 weeks pregnant with twins.