It sounds like her immune system is pretty messed up. I would make fixing that a priority so it doesn't get worse, or allow some future infection to blossom.
Somewhere, there must be a medical doctor that can figure out the cause, and get it fixed. At the very least, I would suggest vitamin D (2 x 5000IU) and vitamin C (2-10 grams, or as much as the body will take before laxative effect.) That should be safe and may give some relief.