20 weeks, hard to breathe, heart racing?

im 20 weeks and for the past two days i've realized that it's becoming a little bit harder to breathe, on top of that, i feel like my heart randomly starts racing (especially at night or when i lay down, i have to sit up when i sleep now). my legs and feet are also starting to swell a lot easier if I don't keep them elevated at all times. did any of you go through this? i feel like it's starting to make me super anxious because I don't know if it's normal or not? i have an appt on thursday so i will definitely bring it up, but just thought i'd ask.