Take a frozen water bottle, put it on its side on the floor, roll your foot on it back and forth while you are sitting in a chair. If you can't freeze it, just chill it. You can also use a tennis ball. First one foot a few minutes then the other. Then again. Sit in a tub of warm water and soak your feet. Wear wide enough shoes with good arch support that are not new for the trip. Bring a second pair of a different brand that are also comfortable and supportive and alternate one day this pair, next day the other pair. The shoes will hit your feet in slightly different ways so the exact same touch points won't take a beating every day. Good fitting, comfortable worn in but not worn out walking sneakers with ties, not slip ons. These methods work for arch, sole, and heel pain.