Facial fungus is a fairly common condition. I recommend you speak with your dermatologist
, or your primary care doctor
to further answer your questions.
Facial fungus, is a subset or many fungal skin infections. Normally, everybody is covered with many bacteria and fungi (or yeasts). These bugs live in the environment (in the soil, water etc) and live on us without causing problems (this is known as colonization). However, every once in a while these bugs that normally cause us no harm can invade into the skin and cause an infection. If a bacteria does it--it is known as cellulitis. If a fungus does it --it is called tinea. It is unclear exactly why or how the bugs switch from doing no harm to suddenly causing an infection. Most commonly, there is a portal of entry--like a tear in the skin from a cut or from a hair follicle. Some areas are more apt for these infections. Specifically for fungus, the warm and dark environments are better--so people often get tinea in their groin (jock itch) or feet (athlete's foot). The face can sometimes be affected--often in men where they shave. This is caused tinea barbarae.
There is nothing you did wrong and therefore preventing it is difficult. Good hygiene such as washing your face is important--but this alone cannot say 100% you will not get it again. Talk to you dermatologist. If you do get recurrent fungal infections this could be a sign of other diseases (for example diabetes).