I got very C, crampy, & bloated about 4 days into my trip, despite taking Miralax every morning. That's very normal for me when on vacation. It makes me SO MAD. Anyway, I also brought Zelnorm with me "just in case." Usually, 1/4 of a pill helps me if I need an occasional "boost" at home, but that didn't do any good on my trip. So I took 1/2 a pill one night, then took another 1/2 a pill the next morning with my Miralax. That did the trick. I went several times that day.
So my suggestion is to bring Zelnorm with you to take if you get in a "bind."