You need to take her to a vet immediately. No one here can tell you what is wrong.
Hello Zoey.....Boy, it sounds like your girl's sick! You don't say how old this dog is.....If it's a puppy, you could be looking at something fatal like Parvo, which you don't have long to treat before it gets out of hand....
You also don't say where the blood is coming from...If it's associated with her diarrhea, it could be anything from parasites to poison....If it's from her Vulva, it could be a kidney, bladder, or Urinary tract infection which would need to be treated with Antibiotics from your Vet...
The hiding is considered a symptom of PAIN!
All of these symptoms are serious! The Paralysis would go along with poison, pain, or possibly Pancreatitis (Which is very painful).
You need to get her to a Vet ASAP, no matter what age she is.....I feel she's in trouble and needs help soon....Please come back & let us know what happens.....Good luck, Karla
Zoey...I've re-read this and I believe you have an Emergency on your hands....This forum is not set up for Emergencies! You need to get her to your Vet, NOW! Karla