Sore throat for 7 days no fever what could cause this? 57 year old male in good health non smoker.

Viral pharyngitis: Most common cause is a virus, for which there is no treatment (and no need for it usually). It is mild and self-limited. Most of these are gone by one week, and if they persist beyond 2 weeks, you should be examined. Mononucleosis can cause this, and is very catchy. If fever develops, pain persists, lymph nodes in the neck, or there are problems with swallowing, see a health care provider asap.