Hi, I'm Dr. Deb. I will do my best to assist you today.
I'm sorry that Lulu isn't feeling well.
The symptoms you describe could be consistent with a number of underlying problems ranging from dietary indiscretion to a bacterial/viral infection or even a foreign body, unfortunately.
It might be helpful to take her temperature if you have a thermometer. Normal would be between 100 and 102.5.
Evaluate her gum color which should be pale pinkish in color.
Feel her abdomen behind her ribcage for tenderness or pain.
If she has a fever and/or her gums are any other color than pink and/or she's uncomfortable in her abdomen, then I probably would suggest that you have her seen since she's been sick for several days now.
But if those signs aren't present, then you may be able to treat her the rest of the day and she'll respond. If she doesn't, then I'd suggest a vet visit tomorrow.
1. Since she's not vomiting and if she is not currently taking any aspirin or nsaid products (I don't know why she would be), , then you can give Regular Strength Pepto Bismol. The dose would be 1/2 ml/lb 2 times a day. For example, if she weighs 10 lbs, then you would give 1 teaspoon at each dose ( 5 mls=1 tsp). It may change the stool color to a gray-black or greenish color though so this shouldn't concern you if it happens.
Pepto bismol should not be given to vomiting dogs since it contains salicylates (the active ingredient in Aspirin) which can irritate the stomach.
2. Consider probiotics such as Forti-flora. These may be available at local pet/grain stores.
3. You could also offer her human baby food but just avoid those with onion or garlic in them.
4. Since she's drinking, you could give her Pedialyte which can help replace electrolytes lost from vomiting and diarrhea.
Yorkies can become hypoglycemic (low blood sugar) pretty quickly so to avoid this problem if she's not eating well, I'd smear pancake syrup or honey on her gums (about 1/2-1 tsp) every several hours.
I hope this helps and that she feels better soon. Deb