We had a hard time with people not believing us or trusting that we were doing the right things for our kiddos. Close family and friends too. It's hard. Harder than I could have imagined. But you basically have to weed out the doubters from your life because you just will not have time or energy for them.
Is finding a good nanny an option instead of day care? Honestly, the difference that you spend on an in home nanny over day care may pay for itself for the lack of hospital bills due to dehydration as well as days off work you may have to take because of sudden illness. There are soooo many variables at a day care and the incidental exposures are much higher. Its also easier to keep more accurate records w/ less cooks in the kitchen.
We have had good luck with our letters from Boston Children's Hospital because Boston Children's holds quite a bit of clout in our area. We have also used the term "Auto-immune disorder" instead of "allergy" because I feel like some people have a weird tendency to doubt the severity of allergies... which is crazy in and of itself, but true.
Good luck with everything. YOu are not alone. Feel free to reach out.
Mark & Julia