Sorry to hear you're having this kind of difficulty. I had a toothache in the middle of my chemo, and actually needed a root canal. I was told that chemo can change the environment of the mouth, so this was a root canal waiting to happen, and the offending tooth identified itself during chemo. I would definitely talk to the onc about this and ask if you should see your dentist. I'm not suggesting YOU need a root canal, but just that any dental issues can be more vulnerable during chemo. Hope that helps.
Hugs & prayers,