Just some info/advice in case things 'do' get worse once you're at WDW:
We were just there last week with DGrD4 and DGrS17mos. DD went to her doc the day before we left with both of them complaining of sore throats, stuffy heads, runny noses, etc. Doc did strep tests and checked their ears and insisted it was just viral. DD asked doc if he could please give her a script for antibiotics to take with her just in case things got worse during the week (we've had this happen before) - he gave her a lecture on how he could not do that... kids take too many antibiotics... she is not a dr and would not know when it was appropriate to use them, yada, yada, yada. So we leave on Thurs morning, travel together, eat together, sleep together (you get the picture

- Guess who calls DD in the MK at 1 PM on Friday?? Yep, the Docs office - to tell her DGrD4s strep test they sent off just came back + - full blown strep - needs to be on an antibiotic immediately (and so does DGrS since it is so contagious). They told her to go up to front of park to Guest Services and find out where nearest pharmacy is and they will call scripts in and we need to figure out how to go get them ASAP (no car we took ME). Thanks, Doc! LOL
Anyway, I suggested going to First Aid and, as always, they were wonderful! They are nurses, and gave DD all info she needed and walked her through the process of contacting the pharmacy they work with that will take all your info, speak to your docs office, fill your scripts and deliver them to your hotel (ours arrived at the front desk about 7 PM, first contacted them about 2 PM) for a $7 delivery fee. Only downside was they do not take insurance, but charge you in full. However, they do send all the forms you need to file with your insurance with the scripts.
It was a great system, great help and support from the Disney first aid nurses - saved us a ton of time, frustration and confusion!
Hope everyone gets well quickly and has a great trip!