i think it's her teeth. Kash does a similar thing sometimes and i've seen his adult teeth coming in... i think he might have to get them removed by the vet... which sucks because he's already gone under anethesia for his neuter, and i really don't want to do it again. but the longer i wait, the more i feel like i'm going to have to do it because his baby teeth just won't budge!!
i'm going to make an appointment for my vet to just take a look at his teeth to assess whether or not it's absolutely necessary to put him under again.
if your pup hasn't been spayed yet, then she'll probably get her teeth pulled while she's under for the spay... i hope that's the case for you. unfortunately, Kash's adult teeth started coming in shortly AFTER his neuter, and not before.