Oh my dear,dear friend. I am so sorry little Billie has to go through this. I am so sorry for the worry, concern and pressure it puts on you. If anyone can find a way to put this in perspective and deal with the concept of angst...you can, my friend.
Your thoughts and analysis are very wise. Although I know nothing about allergies, I do know about managing ones reactions and behavior. From that place, I believe you will get yourself there and it will help.
In the meantime be good to you. And give my hugs to your 2 sweet girls and a wish to feel better soon to Billie.
❤️❤️