as per the details u have mentioned u have just recovered from streptococcal pharyngitis
and now suffering from APTHOUS ULCERs of mouth . thats why u are getting pain , most common cause of apthous ulcers is any stress
, and improper oral hygiene
, some times b-complex vit,. deficiency.
what ever may be the cause ..u start using some multi vitamins with zinc and use CHLORHEXIDINE
containing mouth wash three times per day after each meal... thats it
this will definetly help u..