Are you sure you don't have allergies? I get sore throats from the nasal drainage running down the back of my throat. That drainage also causes a cough. Anyone that has recurrent cod symptoms needs to be tested for allergies.
Have you tried an over the counter antihistamine like Claritin, Zyrtec, or Allegra? Does one of those clear your symptoms? Just food for thought.....
Other than that, wear gloves when out never touching a public access surface, just hand sanitizer, and wash your hands frequently. You could also wear a mask....