26w cramps-no preterm labor

Taylor • Married. Brooks born 8/2015. Baby Eleanora Quinn due May 2018. 💞
I'll be 26 weeks tomorrow, and my husband and I just flew home from vacation across the country yesterday. The day before departure, I was having Braxton hicks & what I would describe as diarrhea-like/period-like cramps, down into my hips and legs so my husband took me to the hospital in Seattle to make sure it was safe for me to fly home. 
 I wasn't dilated, didn't have any contractions while I was there & everything looked good on the ultrasound, including my cervix. They also did the fetal fibronectin test, which came back negative and checked my urine, which was also clean of anything. 
Baby is still as active as ever, but it seems like the cramps just won't go away. I've been trying to drink more water. My question is has anyone had this happen and it be normal? Is mild-moderate cramping at 26 weeks outta the question? I have a small frame, so I'm wondering if it isn't just stretching... Any comments would be great!!:)