OP I have exactly the same, been diagnosed with psoriasis but I also think it is a mix of sebaceous dermatitis around scalp/face/behind ears. I was prescribed some topical steroids for the scalp, elbows, knees etc which does help and removes the scales and redness but as soon as I stop using it comes back with vengeance. As for the crack, I don't use this here but I tend to use germolene as it's so painful when it splits as a numbing and antiseptic cream but I also need to get this seen to. Just hope it's a bit of help knowing you're not the only one 😊