I’ve has a good look and I cant tell. It’s on her tongue and down her throat. It smells, a bit came off when I was checking and it looks like food. I’ve added a photo of the bit that came off too. Sorry, the photos aren’t the best!
Well if you think that is feed, then take a q-tip and scrape it out.Sometimes there is bread leftover from sandwiches in the scraps they get. They also get normal layer crumble.
If it's canker then the removal of the gunk will likely bleed a bit.
I would continue with the Coconut oil and follow the instructions that @azygous gave you in POST#2