That does not sound like a gallbladder attack to me. I am sure you are fine. Our bodies do all kinds of crazy things. I have a sluggish gallbladder and it does not sound like you are having an attack or like gallbladder Cancer to me. Sometimes I get random pains in the stomach and gallbladder areas. Ironically, it is one of the few pains that I really can look at rationally and don't worry about with my HA.
Honestly, look at your vacation this way. Do you want to spend your entire vacation worrying, not taking in the little moments with your kids? Every day that we have is a gift. Every moment has the opportunity to be great and special and something that your children will cherish forever. Try to do some guided meditation tonight, calm your mind, and think about all the wonderful memories that you are going to create over the next week or two with your family.
You are in control. You have the capability to set aside this fear and look forward to a wonderful two weeks. You are going to have a great trip and create great memories. Just keep telling yourself that.