Well IVIG wouldn't be approved unless there was an autoimmune or other immune deficiency present.

Also if you had a pneumonia, you could have received a fluoroquinolone antibiotic for it (Cipro, Levaquin, Avelox).

These antibiotics are quite toxic and implicated in causing PN.

This condition is called "getting floxxed". Recovery from this toxicity is sketchy, with many sites saying it is permanent but a few recent opinions is that after 2 yrs or so there may be some recovery. If you did receive one of the fluoroquinolone drugs, be aware that you can still suffer a tendon rupture anywhere in the body. So do not strain, or lift, or engage in any tension lifting activity for another year or so. However, some people ruptured tendons during average activity, so be careful anyway. These injuries are highly painful and take a long time to recover from.

Sometimes after viral or bacterial infections the immune system goes wonkey and starts attacking the host's tissues. This is where the IVIG may help.