Lowered immune system can cause yeast infections. If your WBC is down from being on an immunosupressant, you can get them easily. I had a lowered immune system from being on 6mp and like I said, eating less sugar helped stop it in its tracks. Maybe I was just lucky.
I don't know too much about
UTIs. What antibiotic are you taking?
Can you get in touch with the doctor who prescribed LDN to ask some questions?
I hope you're feeling better soon!