Can someone give me some answers?

I’ve had diarrhea for over a week now, and three nights ago, I had to go to the ER because my stomach was hurting so bad and it was going to my back as well. They just gave me a bag of fluids and sent me home. The next day I went to my OB, still feeling terrible, I was having a few contractions and the same stomach and back pain. So he sent me to labor and delivery where they said I was severely dehydrated (my urine was basically brown). I got three bags of fluid. I thought I was doing better today, I’ve been able to eat a little bit and drink a little bit more, but my back has started hurting really bad again. They’ve taken my urine 2-3 times and have said nothing about a kidney infection but I am worried. I don’t know why I’ve had diarrhea for this long, but I can’t keep up my fluids.