When you are in pain from mucocitis etc. fluoride treatments may be something that you just cannot tolerate. If you are diligent about your oral hygiene, (which can be difficult when you feel so miserable from the treatments) I would pass on the fluoride until your soft tissues are able to tolerate it. Try the Laclede Biotene product. It does not have a foaming agent (which is in most toothpastes like Crest) and that is one of the culprits in the irritation issue. It has fluoride, though not in Rx strength. If what you are using is painful, it is likely slowing down the healing process too. Perhaps a compromise is in order for you.