Since her collar got stuck in her mouth, she may have damaged her trachea. Your vet needs to take xrays. Most times they can be managed with medications, but if it is severely damaged she might need surgery.
Collapsed Trachea ~ Pawprints and Purrs, Inc.
I'm sure you learned this from your experience, but Yorkies and other toy bred dogs should never ever wear a collar. Their tracheas are too fragile.