@math2468,
I agree with jespah. Funny I got this as an adult had never even heard it. Went to the doctor and they asked if I had been around kids. I said I just came back from Disneyworld so yeah there are lots of kids there.
Any way - the doctor did say it is unusual to see adults with this because it is so contagious. She said usually most kids get it when they are very young toddler age because it is so easy to catch. The symptoms in young kids are usually very mild and often times you don't even know the kid had it. And once you have it you are immune. Why they don't often see it in adults.
It is worse in adults. Very itchy and uncomfortable, but not serious - at least that is what I remember - I would reach out to your doctor to make sure. Also check to see when the infectious stage is - he could likely no longer be contagious by next week. I'd suggest getting all the details from your daughter (how long he has had it, etc.) and then call your doctor.
I am sure if it would be best for you not to go your daughter would understand and would not want you to catch it. Why go through that - would it be easy to re-schedule?