https://greenmedinfo.com/disease/psoriasis

The problem substance section would be the best place to start imo.

Get back to eating organic fruits and vegetables. Clean the meds out of her system and start putting her own urine on the affected skin.

Diet, mostly inflammatory response to gut from diet.

Supplement of Silica can also help. Silica serum applied topically can provide some relief.

Beef, butter, and eggs. Cheap bacon is probably not good.

And good salt.

This will reduce inflammation and once the symptoms are reduced, she can set about repairing her gut biome and slowly figure out what her body was reacting to.