Yup, probably teething. I know you can tape their ears to help keep them up, but it sounds like if they were both up before they should be up eventually. I heard that during teething they can go up and down. You can also make sure the ears are shaved so no extra hair is weighing the ears down. Rio's and Bullet's ears stayed up throughout their teething stage luckily.
__________________   With love from Rio, Bullet, & Alice |