what could cause this?

So today my bf & i went to the dollar store to get our new puppy some more toys. we were just walking around & I'm like "ok, can we check out I can't breathe" so we're waiting in line, 2 ppl in front of us. an older woman of course taking her time counting the EXACT change 😑 then I'm starting to panic bc at this point I literally couldn't breathe, I'm sweating & just want to sit. finally next person in front of us is up & my bf starts laughing bc he thinks I'm joking. finally it's us. I pull out my debit card, insert it & of course the chip thing isn't working so I swipe it, type in pin & just walk out on like grab it all & let's go. I rush to the car & start crying bc I couldn't breathe,was sweating, felt like I was going to pass out & felt like I was going to throw up. finally after he blasted the air & i was sitting I started to feel better. I'm 21wks today. with previous pregnancies when this happened they said my bp was super low bc it happened at the drs office too while they were checking my bp lol but is it JUST bp issues or could I be sugar issues? I get my glucose test in 4wks. I haven't had gd with my other 3 kids..