OP:
These are the things I do when I visit WDW to mitigate against the unique mix that is Florida allergens ... [we live in Canada and visit during winter]. Much of this I also do for any trip. Perhaps some of them may be helpful for your kiddo.
Contact WDW Special Reservations Line: (407) 939-7807 to request a special cleaning/preparation of our WDW hotel room. They have a special form to complete. Be prepared with what you are asking for and why. Search the forums for posts about "VIP Cleaning" and "Allergy Cleaning" to learn more about the request process and what they can do.
Among other things, we also ask for the linens to be washed without fragrance and extra rinsed, and we ask for an extra set of bed linens.
I bring a king size fitted-style allergen barrier mattress protector [I prefer this one as it is high quality, very lightweight, and in a ziploc or compression bag will compress VERY well:
https://www.missionallergy.com/prod...ow-encasings/fitted-travel-mattress-encasings ]. King size because that way it will fit any size bed at any hotel -- the bit extra for a queen bed at WDW I just tuck in. Pillows go into king size allergen pillow protectors [I prefer these ones for the same reason as the company's travel mattress barrier:
https://www.missionallergy.com/prod...encasings/premium-microfiber-pillow-encasings ]. King size again because then they will work at any hotel. Downside is they are white, so it is important to NOT have housekeeping messing with your bedding. Mission Allergy does make a zippered sham in other colours of the same material which also works well. All pillows on the bed I sleep on get the covers.
We request no housekeeping or only trash removal during our stay.
Take allergy and asthma medications in advance of and during trip as directed by physician.
Have allergy/asthma plan from doctor for what to do if allergies and/or asthma worsen during trip, including having additional medications on hand and instructions for when to start them, when to go to urgent care and/or ER etc.
My normal shower is in the morning, but I take at least a rinse off shower each evening to get pollens and allergens off. This actually makes quite a difference, and I do it at home spring through fall, too.
Finally, I wear a filter mask when outside. I like the Vogmask (
https://www.vogmask.com/) and Cambridge Mask (
https://cambridgemask.com/) masks. These are the same masks I wear at home when outside, spring through fall and sometimes in the winter [we'll get thermal inversions and things like wood fireplace smoke sitting at ground level]. They make a significant difference vs allergens. However, they take getting used to, they can get hot and uncomfortable [especially in summer weather], and they DO have an impact on oxygen saturation [mine drops a couple percent while wearing the mask]. If you think a mask may be a way to go, I would strongly suggest talking with your child's physician about it before embarking on that path. There are a lot of options, ranging from simple lightweight masks that won't filter much to masks like the Vogmask and Cambridge which are rates N95 or N99 if fitted properly, to 3M medical masks rated N95-N100 [when fited properly, and which fit better, though I don't know if they have child sizes]. Another downside of the masks is people notice them. Sometimes they make comments, not all of which are positive. At WDW most of the comments are kids asking why I'm wearing it
Good luck finding the cause and solutions. Hope your kiddo is feeling better now.
SW