3rd trimester flu or pregnancy symptoms!?

I'm almost 28 weeks & have been feeling awful lately!! I've had horrible heart burn to the point that I almost vomit because of it. I've also been having a really hard time breathing. It feels like a bad cold, and I get that itchy, congested feeling in my chest. I also feel like there's a pill or something stuck in my throat, even though I haven't taken any! I'm nauseous and have diarrhea. I know some of these things are pregnancy symptoms, but I feel so horrible and am hoping it's a flu that will pass quickly. Any one else have some of this in the 3rd trimester? Did it stick around for the whole thing??