Short of breath when laying down (even on left side!?)

I’ve noticed for the past 3 days I feel short of breath, sort of like i’m suffocating when I lay down— no matter what side. I normally sleep more comfortably on my right and even that is pretty uncomfortably lately. I notice it more when it’s after I eat but it still happens even on an empty stomach. I don’t know if it’s important to note that I am anemic but have been taking iron every other day (per my OB’s advice).

eta: I’m 27 weeks today.