I had a flu (or just a cold) no fever, aching body, night sweats, which I recovered from except minor wet cough. Still very tired. Is this a concern?

Typical symptoms. Your symptoms are typical in convalescence following viral infections. They may linger for days to couple of weeks, fatigue specifically. Rest and hydration are critical. Any sudden worsening should be treated timely as suprainfections are common and immunity is transiently weak.