Does she wear cotton clothing and underwear? I find synthetic clothes very uncomfortable and I like all my clothes to have a high cotton content, preferably 100%. All my knickers are 100% cotton and I even bought a reusable cotton sanitary pad to use, although I haven’t been able to test it yet ’cause my period hasn’t come in months. I got it partially for environmental and partially for comfort reasons (I find those plastic pads can get very irritating).

Hope that helps (btw I might not even have CAH but I’ve had that problem and it’s fine as long as I stay in cotton).