I have yellow pus in the back of my throat.i went to the doctor today and my strep test was negative.what do you think i may have?

Post nasal drip: as summer starts the allergy season is more common than a bacterial infection. Fevers, malaise, loss of appetite, painful swallowing would go along with a bacterial throat infection. This time of year post nasal drip would be the alternative thought. Try using antihistamine or Claritin to dry up and if throat is better than plan for next year as well.