Yeah. The vet said a swelling like this can be a virus that can turn into cancer. So I'll just see.
Thanks.
Heres a bird looks similar to yours, have a look at the thread. Look inside her mouth to see if there is anything in there,
https://www.backyardchickens.com/t/850107/i-need-to-know-what-it-is#post_12696957