Can you have mono w/o classic symptoms? My teen had strep and meds. After, he had 8 days of a sore throat, swol lymph--no strep. Dr felt it was viral/allergies. Sore throat/Runny nose last week. Fatigue low fev this week.

This definitely. sounds like it could be mono. The symptoms you are describing are actually classic for mono. Mono presents differently in people, so it sounds like, if he's never had mono, he should be checked (blood test, i.e., mono spot and more importantly, EBV (Epstein Barr virus) titers.