Alright this is what I would do:
*skip her next meal
*for the following meal do mashed potatoes (with no milk or butter mixed in) and boiled lean hamburg (or whatever meat she is not allergic to)
*continue the flagyl/metro
*personally I would not give the amox, but i'm not a vet, so don't take that as truth, but the flag is an antibiotic also which does not inflame the bowels like amoxi can.
Hopefully this will stop the diarrhea, even though I'm sure her stool will still be loose when she goes, but she shouldn't be having anymore accidents.
"All changes, even the most longed for, have their melancholy; for what we leave behind us is a part of ourselves; we must die to one life before we can enter another." -Anatole France