The FAD and FMN are both from B2, and the most available form is called coenzymated B2, such as Source Naturals coenzymated b2.
Very interesting about the floaters, I've never heard that explanation. Yeah, I have floaters, the pain around the eyes, nose, general face pain in that area, it comes and goes. Is yours constant?
Thioredoxin reduces (neutralizes) the free radicals (oxidative stress). I'll see if I can find the thread where I found out about it for you.
The cause? Something to think about. Maybe just reactive oxygen species from the virus? ROS is the acronym, I'll see if i can find some links.