Ok it sounds as if she may be going through a bout of colitis or inflammation of the large bowel. The signs can be very intermittent and can vary in severity, from normal stools to mushy to very soft, all even within one day at times. Seeing mucus or blood is not unusual as well in some cases. There can be a sense of urgency to move their bowels and many of the pets will strain when having a BM, which to the owner can almost look like they are constipated. Many pets with colitis have GI discomfort and some will even vomit.
Colitis can have many causes including intestinal parasites, dietary indiscretion, food allergies or intolerances, metabolic disturbances from internal organ malfunctions, viruses, toxins, cancer or even stress. Your veterinarian will want to know the history of her signs and will need to perform a physical exam to help rule out the causes mentioned. They may perhaps suggest a change in diet or medications. Make sure they also perform a rectal exam to evaluate her anal glands. A stool sample analysis is a very important part of getting to the bottom of this as intestinal parasites are one of the most common causes. Since this has been going on for days now without resolution, I would have her evaluated by your vet soon.
Until you can get in contact with your vet, I would fast Ruthie to give her GI system a rest. Since she is an adult dog, a 12-24 hr fast will not hurt her and will let her gut calm down. Continue to offer small amounts of water at a time. When you do begin feeding her again, you will want to offer frequent, small meals of something very digestible for her. These would include items like boiled hamburger or chicken and rice or pasta. No sauces or gravies, but a little non greasy broth would be OK. If the stools improve, I would continue that for a few days and then slowly wean her back onto her normal food and feeding schedule.
I hope this is helpful. Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please reply so I can clarify for you.
My posted replies are for general education only and not meant as a diagnosis. Only after a thorough veterinary examination can a diagnosis for your pet be made and specific treatments be advised or medications be prescribed.