She is keeping her tail down like it is pain or her anus is in pain. She doesn't want to sit down and shivers.

Would help if you told us how old your dog is. When was the last time you had her anal glands drained by the vet ?

Well I think you need to take a visit to the vet. And if you have no money then I'm sorry but you are not fit to take care of a dog. If you don't take her to a vet and its serious your going to watch your dog die.