Help treating flaky skin on face after showering

[CS373]

I went to the doctor about my seborrheic dermatitis that I have in my nasal folds and inner eyebrows. I was told to use prescription ketoconazole shampoo in those areas. Despite using this for a couple weeks now no improvement in my symptoms. Every time I take a shower cold or warm those areas become infested with flakes/peeling-like skin once my skin dries from the water. Even on the off days when I don't use ketoconazole it will do that. However the next morning the flakes and such disappear and it stays away until I take a shower.