Definitely not false pregnancy, since she's spayed. Even if it was, that wouldn't cause the symptoms you've described. As JBun said,
this is a medical emergency. A vet trip is an absolute must.
Not eating and/or pooping for 8-12 hours is a medical emergency for rabbits (commonly referred to as GI stasis). There are at-home remedies that can be tried in the early stages, but at this point it's absolutely vital to take your rabbit to the vet, as GI stasis can easily become fatal within around 24-48 hours. Rabbits have a very
unique digestive system that NEEDS to be constantly moving along. If there's a blockage/hairball or the rabbit stops eating for another reason (usually pain - tooth issues, gas, illness, injury, etc. can all cause GI stasis).
As for the watery poops... are they truly watery (like diarrhea)?
If so, then that's also a very serious emergency as it's nearly certain that your rabbit has some sort of illness/pathogen. By the time rabbits actually show signs of being sick (as prey animals it's instinct to try to hide when they don't feel well), they're usually in critical condition.
However, if by "watery" you mean "slightly moist and very mushy" and they look stuck together... and if they *really* stink if you mush them... then it sounds like you're talking about
cecotropes (
click the link for pictures), which are an entirely different (and much less serious) issue. Cecals are normal, healthy and necessary... but are also supposed to be ingested directly from the anus in order to pass through the digestive tract a second time. If you're finding them in the cage, that means your rabbit isn't eating them (or at least not all of them). Common causes for this are:
1) age - young bunnies can ADD and forget to eat them
2) inability to ingest them properly - typically caused by obesity and/or arthritis, sometimes also injury
3) diet - too rich a diet (almost always, this means too many pellets) can cause a rabbit to produce more cecals than they actually need, so they abandon some or all of their cecotropes.
Your rabbit is far too old to be offered unlimited pellets. An adult rabbit's diet should be about 80% grass hay (timothy, orchard, coastal, bluegrass, etc... if you feed a cereal type hay like wheat, oat, rye, etc. then you need to remove most or all of the seed heads (ie oats or w/e) before offering it)). No legume hays like alfalfa. They should also get a very limited amount of pellets. The
House Rabbit Society website has a great selection of articles about diet.
This article in particular lays out what an ideal diet should look like.
Mind you, if she's being free-fed pellets and isn't eating hay, you shouldn't just abruptly switch her to a tiny amount of pellets and a hay rack. Gradually reduce the amount of pellets she's getting while offering unlimited access to grass hay so that she can get used to the idea of eating lots of hay. In the end, a rabbit should eat a pile of hay that's about the same volume as their body each day (semi-loosely piled, not super compressed the way it is when it first comes off the bale).
I hope your bunny is doing well and you've been able to get her to the vet! My bunns and I will keep her in our thoughts.
