Grind up a doxycyline tablet, put some on a denture adhesive and stick it on sore – one application doubles pain relief over time
Oral Surg Oral Med Oral Pathol Oral Radiol. 2013 Oct;116(4):440-6.
Single application of topical doxycycline hyclate in the management of recurrent aphthous stomatitis.
Vijayabala GS, Kalappanavar AN, Annigeri RG, Sudarshan R, Shettar SS
http://www.ncbi.nlm.nih.gov/pubmed/24035110
If patient had recurrent issues, could have several doxycyline tab dispensed and buy own Polident or something .Cheap and effective.