31 weeks pregnant and im worried that labor is coming soon!

31 weeks pregnant with my 2nd baby. For about a week now I've been having diahreha. It doesn't matter what I eat whether its a full course meal or a ham and cheese sandwhich or if I don't even eat anything at all I still have to run to the bathroom. And it just started bc a week ago I was fine. I also am having low back pain like someone is trying to rip out my back. I have no appetite. My heart rate sky rockets for no reason. Even if I'm just sitting on the couch watching tv and when that happens I get really hot. I am also having vaginal pain like she is tryint to stick an arm out or something. It doesn't matter how I lay I still hurt. A warm bath doesn't help and neither does a pillow between my legs. What is going on? Like I said this all started about a week ago and feels like its gradually getting worse. I didn't have any of this with my son...someone help!! I have an appt auguest 10th but idk if I should wait that long????!!!!!!