Traveling/Vacation are two I struggle with, heck, when my hubby is on vacation I get the "I can eat what I want" mentality which is weird because I can eat what I what any day, no one judges me nor what I eat except me.
I guess try to figure out if it is stress eating, reward eating, escape eating name it and claim it. Traveling takes you out of your routine so for me it becomes an all or nothing if I'm not careful. I try to keep in mind, especially if I am traveling in my own country that I can have any of this food any time, these aren't special M&Ms only available in the airport these are the same M&Ms I pass by everyday in the vending machine at work.
Good luck, drink lots of water-even though it's not special water either