Aside from pureed and soft foods, there are a few herbals you might consider which are also used for toothaches in people. Unfortunately, there's very little information available about safety for pets regarding most herbal treatments - as far as I can tell, the ones that should be okay (at least for short-term use like this) include: marsh mallow (Althaea officinalis) root, blackberry or raspberry (Rubus spp.) root, mulberry (Morus ***** [edit: black mulberry - because the species is getting kicked out by the censor for apparently looking like a misspelling of a racial slur instead of a plant name ]) bark, strawberry (Fragaria spp.) leaf, plantain (Plantago spp.) leaf, and mullein (Verbascum spp.) root. Licorice is also a possibility (one I know firsthand to be effective), but absolutely not without a vet's okay because certain conditions would contraindicate it's use. If you do choose to use any of these, administering them as a cold tea shortly prior to feeding would probably be most effective.