If you haven't tried apple cider vinegar it really does work and tea tree oil is great too so I started by combining the two. Great for your scalp but dries out hair badly.
I now take about 1/4 cup apple cider vinegar, 1/4 cup very strong brew of chamomile tea (2 tea bags left for about 5 minutes), a big heaped table spoon of coconut oil melted, and a big splash of tea tree oil. Shake up in a spray bottle & spray onto scalp & massage in. Leave for as long as possible. It might sting a bit at first but that goes away pretty quick. Then wash with a psoriasis friendly shampoo. I use Thursday plantation tea trea shampoo. Condition & if need be rub a little coconut oil through the ends for leave in conditioner. (be careful to just use a tiny bit).
Keep solution in the fridge & warm in hot water to melt coconut oil before each use & shake well.
Hope that helps someone else get some relief!