That sounds horrible. Poor guy. I don't have any suggestions, but I do want to say just watch him and maybe it's not a virus. I threw up after our first day at the parks when we went last year and was sure I had a virus and spent most of the night trying to figure out what to do, but I was fine the next morning. I think it was just the traveling and eating different (rich) stuff. P&PT that he's ok.
I guess I would probably try to figure out a way part of the family could go. Sorry you are having to deal with this.
DS - Feb 2010
DD - May 2012