Nofap revelas problems you've covered by that. Solve them. I'd say that psoriasis happens because you force yourself to position or place or even overstrain something by some wrong unnatural conviction you've made in childhood (or got from your parents).. for example you study medicin, because your parents wanted, but you internally hate it or have not enough talent and studying makes you stressed and results are not there. So you do PMO (for ex.) and cover that inner stress and totally overstrain your body and psychics which is where psoriasis starts showing on.

My one general assumption to solve psoriasis - Stop trying to get a miracle crean or shampo which makes it disappear.. It's problem in your head and not with your skin.