Pain on teeth and gums, trouble swallowing, chewing hurts, and swallowing, white spot under tongue and on gums.

It's a girl that's feeling this

It could be thrush, a yeast of the mouth.
Read the below site from start to end. Don't skip any of it.
Candida Yeast Infection Information, Advice and Relief | Candida Yeast Infection (http://www.candidayeastinfection.com/)

It could be thrush, a yeast of the mouth.
Read the below site from start to end. Don't skip any of it.
Candida Yeast Infection Information, Advice and Relief | Candida Yeast Infection (http://www.candidayeastinfection.com/)
My first thought was thrush, or maybe a host of canker sores. Her doctor or dentist would be her next place to go. She definitely should not ignore this and allow it to worsen.