it sounds like stress colitis - yellow jelly poop with blood in it
Probiotics will work - i use dds plus from vitamin shoppe
Dds-Plus Capsules by U.A.S.Laboratories - UA-1010 - at The Vitamin Shoppe
if this does not work then when you get back from trips do tylan powder for a week after that is a mild antibiotic but bitter tasting so you may have to have compounded by compounding pharmacy with some chicken flavoring - ask vet about it - it is less of an antibiotic than metronidazole