I don't know anything about
this condition, but I have taken Montelukast for years for my cat allergy and it works great for me. Without it, I can barely breathe around my cat. And wow, I bet you are sleeping a lot with that much Benadryl.
Do you have to take these forever or just for a while?
Edit: And I used to take Zyrtec as well. It stopped working and I now take Allegra and have for a decade. I don't get any side effects with the Singulair or Allegra, if that's any consolation.