911! Should I go to the doctor??

Hi girls, I'm 28 weeks pregnant today and have had a really easy pregnancy so far until now. Last week I got the flu and today is day six of diarrhea, body aches and severe headaches. The strangest part is that I have the constant urge to poop and even after I go, I have so much pressure down there to keep pushing. I swear it feels like I am going to deliver this little boy in the toilet! The pain shoots down my legs, my head throbs and if I get off the toilet to do anything else, it's only a matter of minutes before I'm running back. What is this???