Very Concerned, Adviced Needed...

Well, you can't stop it NOW..she's a puppy, and puppy's mouth, puppies teethe, and puppies get excited.

Keep doing the ouch method and ignore her for a few seconds until she calms back down.
If after you say ouch, she doesn't stop, stand up and turn around with your back to the pup and just ignore until she calms down.

Australian shepherds and border collies are notorious for ankle nipping and herding behaviors like that, but as long as you keep them stimulated mentally and physically and work on bite inhibitian now, you should be okay.

Every puppy is going to mouth and nip, but a dog with good bite inhibitian will be excellent at knowing what to do and what not to do.

I adopted a dog from a pound a few years ago, with my mom..and literally this dog had the best bite inhibitian I have ever seen in a dog. I could literally stick my hand in his mouth and he would hold his mouth open because he knew not too touch teeth to skin. Someone had obviously shown him what to do and what not to do. Sadly he tried to eat our cats and our cats became so scared they would urinate/defecate on themselves when they smelled him and we had to bring him back.(Dang shelter told us he was excellent with cats...BS)

N.I.L.I.F is nothing in life is free, it is a sticky in the training forum.

Most herd by going after the ankles, so many can mouth the ankles if not taught properly.

Bite inhibition is simply knowing not to apply pressure or use teeth when playing with a person, or another dog.

That's what your doing when you say OUCH, and ignoring for a few seconds, or however long necessary.

You are showing the puppy that mouthing is not acceptable and it WILL stop playtime.