I am Dr Mbong. Low Ferritin is very unlikely to cause swollen lymph nodes
With the severe fatigue
, weakness and night sweats
and past history of Mono, some other cause is more likely. The cause may be affecting your blood cells and body iron stores, the reason for the low ferritin.
The CT scan
can help oriente the diagnosis. Your physician will however need to prescribe a full blood count, some other blood assays and biopsies of the lymph nodes alongside the CT to better determine the cause.
Regards and quick recovery,