Hey mate. I’m in a similar situation where I’m diffusing all over, but if I grow it out and keep it dry I get okay coverage - it’s gotten pretty bad pretty quickly though. I reckon I have some idea of the pain you’re going through - it’s bloody tough. Try to be proactive about it. Go to a derm/hair specialist and tell them what’s happening, get some bloods done etc... I’ve found using Nizoral 2% with a tiny drop of tea tree oil and leaving it in there for 10-15 mins before rinsing has helped with the dermatitis and itch. You’ve kind of got to be liberal with it too and if you see hairs all over your hands just know they were destined to come out anyway. No home run, but it’s certainly helped. I do that every second day. In terms of finasteride, I also doubt it’s effectiveness, but I’m also somewhat early in to using it so I’m sticking it out. Schedule more frequent visits to the derm/hair specialist to track where you’re at and discuss your concerns.
There’s no easy solution here and it’s a shitty position to be in. Do the best you can and stick with it.