I always tend to over water this probably one of my main problemIt could be from not letting your soil dry out, that is one cause of them and they will eat your roots, turn the top 2 inches of soil over and let it dry out
do you put the Neem oil directly into the soil and if so how muchi had the same problem dude. I also had some mold and fungus.
Neem Oil took care of both problems, and its organic and all natural.
Neem Oil is amazing, look it up.