K.B.
She should have a vet exam if she has not already, but it could just be the gums being inflammed while she is teething. Or she could have some residual food (wet or dry) sticking around on her teeth or gums. You can start getting her used to having her teeth and gums brushed by introducing your finger with some wet gauze wrapped around it and gently rubbing over them. But it really seems rank, get her checked out at the vet.