You are obviously doing the right things, including mouth washing after drug use
and you are correct that the Spiriva
and Duo-neb do not contain any steroid.
Unfortunately, some individuals develop allergy to the ipritropium in the Duo-neb or to Spiriva and the drug simply irritates the membranes of the mouth allowing the thrush to take hold.
That you also develop candidiasis under your breasts suggests that you might, for some reason be predisposed to this infectious agent.