Picky Pottier

Lily, unlike Lola who treats the whole world as her toilet, is a very discriminating pottier. Of course we had our housebreaking issues with her when she was a puppy, but she has not had an accident in the house for months...until yesterday. The thing about Lily is she is very picky about where she goes #2. When the weather is bad, she hates even walking on the wet grass in the backyard, let alone going to the bathroom there. What I can't understand, though, is that even when she clearly has the urge to go, she holds back...for no other reason that I can tell aside from the wet ground. She whines and whines, and we take her outside over and over again, but she simply won't go. It's really frustrating for us, and probably for her, too. Since the past few days have been very precipitous, our backyard is now a swamp, and Lily has not been a happy camper. Yesterday she was doing her normal routine all day, and even though I took her down the street and got her to go a little bit, it apparently wasn't enough because we found a large amount of excrement, shall I say, on the floor in the entry. It obviously wasn't Lola's, but it was surprising because Lily hasn't gone in the house in such a long time. She must have really been desperate. I feel bad for her, but I wish I could figure out a way to get her to go when it's wet outside. Any suggestions from you faithful reader(s) out there?