Hi Franceen.
Two of mine are just like that, my oldest & my youngest. Any slight change in diet & they get the trots.
You're doing the best thing, sticking to the chicken & rice for a few days. you could add a bit of dry toast if she wants something crunchy as a snack.
Just a couple of things.
When did you last worm her? The mucus can be a sign of that, especially with the voracious appetite.
If you've done that recently it could just be an upset tum. The best advice I've had recently is from a new young vet they've got at my practice, seconded by the old nurse there who has Yorkies & swears by this too. It's called Promax, a paste that comes in a tube. Last time my littlest had the runs, the new vet gave her this instead of pumping her with antibiotics. It's very gentle, a mix of probiotics, an anti-inflammatory & something to sort the diaorrhea, you give it till the trots stop. He says he wouldn't be without it for his cats & the nurse swears by it for her Yorkies.
I got the first lot from the vet but it seems to be available without prescription from some of the online vet pharmacies where I buy Tansy's heart pills.
Hope this helps a bit.
xx
Meggie