I am sorry to hear you are worried about your dog. I am a veterinarian, and will do my best to help.
The clear slime from her anus is mucus. The lining of the colon can produce large amounts of mucus, usually when there is irritation to the lining of the digestive tract which can be caused by parasites, colitis, infection, or a blockage.
If she is not eating, is she at least drinking?
If you check her gums, are they a normal pink color, or do they look pale?
The clear substance just tells me she has colitis, inflammation of the lining of the colon. This can be caused by many conditions. Not eating tells me this could be serious and that she probably needs medical attention. If her gums appear pale rather than a normal pink color, I am even more concerned. If she were my own dog, I would start with a good physical exam: feel the internal organs and lymph nodes, listen to the heart and lungs, check gum color and temperature. Depending on what I found, I might treat with nausea medication, or take Xrays or do blood tests.
I am also worried she could be dehydrated after not eating for 2 days and if she is dehydrated that makes whatever is wrong with her even worse.
Let me know what other questions you have. Rebecca