Can vinegar br used to heal a sore throat?

No. Only penicillin V or Azthromycin should be used in adequete doses for adequete period. Strep throat will be alright in most of the cases of it's own, in three days, with out treatmnent. (Or inspite of your treatment, as teacher said.) But you may have one of the most deadly disease at hand. after three weeks. Rheumatic fever. If you do not treat it adequately. Cold and sour things will worsen the symptoms.