Aww I guess the first trimester symptoms kick right back I'm for your third..): I'm 32 weeks and I just been throwing and feeling horrible.
It could be your bodies way of preparing for labor, like its emptying out our keeping anything from being in your stomach when you have your baby. Keep hydrated though.
I've read we can get flu like symptoms before, and during, labor. Nausea and diarrhea mainly. I actually had that hit me around 37 weeks really badly but didn't go into labor. It took a few days before it finally let up. I feel for you! Get lots of rest and drink plenty of fluids.
If it's super hot out that could be your problem. That is my problem I've got to eat cold stuff.. fruits raw veggies deli meay
You could be in labor. They say flu like symptoms sometimes mean labor is coming. Good luck. ;)