I have a sore throat, what's the cause?

Viral infection: 90 % of cases its a viral infection, especially in this flu season. It could be also a steptococcal pharyngitis if you have fever or white patches on the tonsils. Infectious mononucleosis is a another viral inf. Which is a possibility. If the symptoms stay for 5-7 days and resolve it is most likely a viral inf and don't be hesitant in taking an antibiotic before that. Talk to your family doctor

Unsure: Sore throat is a symptom which is associated with many conditions. Do you have a cold or flu? Then it's normal to have a sore throat. If not, it could be reflux or any of a number of other conditions. Please get to a primary care provider to review your health status, especially if you're not better by 2 weeks from when things started.