aphthous ulcers can be caused by anthing that upsets your biological equilibrium- ie a fever, a simple cold. medications. stress,period etc. theu will run threi course between 7-10 days as a rule. avoid acidic drinks and food as a matter of comfort. if there is a pharmacy nearby see if they can mix a 50/50 mixture of milk of magnesia and elixir of benadryl shake it and rinse and SPIT with around 15 cc per use. repeat every 3-4 hours or just before eating. have used this old remedy sucessfully in patients for over 35 years. once prone to these you can expect they can reoccur in the future