Oh my gosh I know how you feel. We were set to go to disney in January (surprise trip) & the day before we leave, my ds has 104 fever!!!! I flipped out. Brought him to the doctor & took doctor aside & said, "help- what do i do, we're going to disney tomorrow & he doesnt even know". She checked him out & strep was negative, but she wrote me a prescription 'just in case' the 24 hour strep came back positive. She told me, it looks like a virus- go on your trip- and even if he is sick a couple of days, better to be sick in disney than here!!! So... the next day we leave to disney via the auto train (it was only on the train that the kids figured out what was going on). And my ds says, "NOW I know why you were freaking out about my being sick." That night he had 103.8 on the train (but he was so happy...) we brought tylenol & ibuprofen with us to get him through the night.
The next day, when we arrived his fever was down at 102.
And the following day, our first day in the parks- he was at good ol' 98.6.
Take your child to the doctor, so if it's something that needs meds- you can get it now... just for some peace of mind. But you do have 6 days, most things run its course by then.
G'luck and have fun!!!!
BTW.... try to keep your kids SEPARATED!!!! I had my sick ds, wearing a painters mask when they were in smaller confines like the car. Thankfully younger ds stayed healthy!