If you have psoriasis you shouldn't wash your hair everyday - it will dry your scalp and make it worse. If you are considering dreadlocks then you could have these but it would mean more care needed.
I have no idea about your hair but, as I'm sure you know, avoid yeast and yeast products and try some magnetic therapy for your psoriasis. Porridge is also good but goats milk is better than cow!
Then you can do what you want with your hair! Happy healing.