I'm so sorry that's the case! We had it happen on our trip in Jan. that ds5 was throwing up and .... the other end the night before our flight. Stopped at around 4am and we had a 10am flight booked and thought ok we'll just water and some pepto chews and not let him eat. Then ds8 started throwing up and stuff at 7am. DH ended up canceling his and ds8's portion of the flights while I took ds5 and we made our flight. I ended up getting sick when we got to the hotel. It was literally the worst! DH was able to get on a flight out the following day w/ ds8 but it costs us an additional $150. If your guy is really sick I would try and call the airline and hotel to see if you can change things around. Also a lot of credit card companies have
trip insurance built into them if you paid with that card for your trip. You do have to go a doctor for a note but if you can get some of your money back. Even if you have to go a day later then planned it's better then dealing w/ a sick kid on the plane.
On a side note about needing a out of state doctor, I did have to go to an Urgent Care in Florida while on vacay w/ my cousin. I literally just googled urgent care near me and then looked at reviews and went with the closest good one. Good being a relative term, a lot of hospital/doctor reviews aren't that great because it's mostly ppl complaining. The insurance did pay the cost and I was able to find a CVS close by to fill my RX. And in addition to that the doctor who saw me about the rash on my arms, asked me what I was doing about the lump on my thyroid. I was like.... ummm... what lump?! It turned out to be a benign goiter but sometimes those things happen for a reason!