Oh, can we see pictures? I’d love to have an avian vet! Mine won’t even run a fecal float!My avian vet told me not to use wood shavings or mulch of any kind when I was having issues with bumbles. She told me to have dirt or grass only in their aviary, no rocks either. And to use only hay or straw for bedding in their barn room. I was having constant issues with bumblefoot before I followed this advice, and when I switched 3 years ago I haven't had a bumble since.
I do have a HUGE aviary, divided into 2 sections so the grass can grow back. And the hay/straw inside their room needs to be changed weekly or it molds.
Obviously, some people are using mulch with no problems. But if I use even pine bedding just for sleeping my ducks gets huge sores on their feet.