How common is it to have cfs after covid? it feels like every night i get extremely tired sometimes during the early night and my whole body feels really tired. im 2 weeks almost 3 weeks post isolation. is this common or is it cfs?

Post-COVID syndrome ("long COVID") can cause symptoms similar to chronic fatigue syndrome (also called myalgic encephalomyeltitis, or ME). Discuss with your PCP. There are providers and clinics in most major metropolitan areas that are studying long COVID and may be appropriate for referral. If your PCP isn't on top of these issues, ask for an infectious diseases consultation. Good luck.

Noting that chronic fatigue is a not an uncommon issue following COVID-19 infection, and indeed, at least 30% of those who recover appear to have some emotional or cognitive issue over the next 6 months. There are medications to ameliorate fatigue syndromes, and an experienced internist can help mitigate the symptoms.