Mom to child would send flags that it was more parasite in my opinion.

First, use zero soap, just warm water daily and wash rag. A little clay could be used if you had to, but daily water works just fine.

deworming and diet would be the main goals and the adult could do sitz baths and get the flow corrected. IF anything is coming out the skin and not down the toilet, then flow is obstructed (constipation).

IF parasites is the problem, the skin/scalp is irritated and the body responds by skin oils, etc.

Have any pets in your life????

MH