Hey man
Sorry to hear you're going through a rough time. Rest up and take good care.
I don't know if you've found the same but I get worse at the turn of the season, and many with autoimmune diseases have reported the same. March/April and then again Aug/ Sept I'm always worse. It just helps knowing to prepare for the down time and to plan accordingly. Maybe have a think and see if you're also getting seasonal change dips on top of not having recovered after the flu.
Take care
Lizelle