Lots of lightheadedness in 2nd trimester?

Tori
I am 13 weeks along with didi twins. This week I've had a few days where I'm so lightheaded and short of breath that it's difficult to do much of anything, let alone chase my 15 month old around the house! I literally have to just sit and do nothing. I had a lot of crazy symptoms with my first pregnancy, but nothing like this. Is this common to multiples pregnancies?