Sick all night

So I'm kind of worried.
Last night I woke up at 2:30 with sever stomach cramping. Went to the bathroom and couldn't go, I've been constipated most of my pregnancy. So I was trying to keep track of how often and how long this pain was because I was nervous there were contractions. They were between 5-10 minutes apart. I eventually was able to go a small amount, normal looking stool, at least similar to what it's been like this pregnancy. Then I almost throw up and stopped myself because I got scared maybe I'm dehydrated and didn't want to lose my fluids?
Well then the cramping got worse, I eventually had horrible diarrhea and had cramping/pain in my back the rest of the night. 
I've been trying to drink a ton since that happened but I'm still feeling pain overall, but no cramping like last night just a full ache.
Anyone else have any experience like this? I was close to having my husband call the doctor on call but then the cramping subsided a little so I figured it wasn't necessary.
Also important to note, no bleeding, no water break and baby was moving like crazy the whole time.