PDA broth, or any liquid medium, like Richards Solution, or Czpek Dox

You have to determine which fungi you looking for, whether it is obligate or facultative parasites, after that, I can give an appropriate answer for isolation and identification.

Good luck

To Jawad's point, I think you;'ll need to develop a reproduction of the disease in the lab so you can identify the etiologic agent(s).   Think of Koch's postulates..

Thank you all :)