Mystery Clear Snot Returns

[The_Dutchess]

Grr...
So the rabbit that died of a heart attack, Bandit? He was sick a lot. He has a gut bug at one point, and sneezed a bit but no matted paws or colored snot, just clear wetness around his upper lip/nose area, that I am assuming to be clear snot. Now, all my mini lops drool, but wouldn't drool be at the corners of the mouth and near the chin/lower lip? I gave him some homemade pedialyte and it just disappeared. Then it came back, then it disappeared again. Well, this morning my PREGNANT mini lop doe has clear snot 2 weeks after Bandit died. What could be causing this? Is there something like a common cold for bunnies? Or is it (I don't even want to say it) a type of the dreaded P. virus?
I just want to know what's going on so I can get rid of it, and now I'm worried my doe is going to abort her litter or that they won't be healthy. Plus, it's my doe's first time. She does NOT need any extra stress on her body.

 

[Zinnia]

How are they housed? I might suspect something environmental.

 

[The_Dutchess]

They are in hutches in my backyard. Two hutches are up against the fence, facing a juniper tree for wind protection. One hutch is up against a shed, and the last hutch is facing the other hutches and is positioned between the juniper tree and the fence. We do have a LOT of pollen right now, could Lily be allergic to pollen? She is the only one showing symptoms, and she is eating fine, otherwise healthy, if quite pee-stained. We have 9 holes and all hutches are facing each other, about 4-6 feet apart, in case that matters any.

 

[Zinnia]

My first thought would have been insufficient air flow, but that can't be with what you've described.