just read the whole thread so what meds is your baby on just metronidazole sorry if i missed this ;(
goat milk is good as it is the closest to the mothers milk you can use goat yogurt as well as a probiotic 2 hrs after the antibiotic - you can get it at lassens or whole foods just a small amount
Coccidia is a tough one especially in a tiny.
here is some info on coccidia
Coccidia (Coccidiosis) in Dogs: A Cause of Diarrhea
I personally have not dealt with this one
so sorry you are going through this