Toy poodle 5 yrs. Old has stopped drinking water, it's three week now, I had her to the vet two weeks ago for vomiting and diarrhea which cleared up with meds and prescription id food, she only drank water if I made a soup out of her food, until she got sick she drank water fine. SHe's eating food fine but Im worried. If I try her food dry she goes without water, she is uninating normally. I don't understand, should I take her back to vet and get blood work. I am very worried, her poohs are mushy still. Could she still be sick?

Yes, you really do need to get her back to the vet as soon as possible. Just by itself, dehydration is a serious issue. She may very well still be sick. Whatever was causing the original symptoms may have been misdiagnosed or mistreated. I imagine they will want to get blood work on her, which would absolutely be in her (and your) best interest.