I could not find a reason for it in my case. I housed two dragons together and I thought the one that got the fungus was just having a bad shed. After some time, I realized it wasn't a bad shed and got her to the vet. I asked the vet if I should quarantine and he told me that the other one appeared completely healthy and if it had already been a couple/few weeks and the other female had not gotten it, then it would probably be OK to keep them together.
I had plans to separate them, bought another tank and light and then saw the other getting better after being treated and didn't bother. The day the sick female went to the vet, she was 165 grams. It's been 6 or so weeks now and she's up to 300+ grams.
My sick female also had a calcium deficiency. I don't see how that could cause fungus. The only other thing I can think of is the female that got sick has a habit of rolling around in the feces
That's the only thing I can think of
FYI, the calcium deficiency was caused by my misunderstanding of the supplement I was usingThe problem has been corrected and I have their supplements arranged by day of week along the side of their tank to ensure they get what they need from now on.