Yesss it's been bothering me for a couple weeks lately. I asked my doctor and he said it was totally normal and when it happens just relax, lay down, kick your feet up.
My heart rate is faster and I get out of breath easily as well. Not to the point of fainting though. Although a faster heart rate and breathlessness is normal for some women
I'm not sure but I'm 32 weeks and get the exact same way. When I get that way I have to sit for a few minutes.