Katy,
Reading your posts is so familiar to me...I can feel your pain 
. Here is my story, I am sure you will relate: about a year ago I began a slow decent to horrible cracks and lesions on my hands and feet. At one point my feet had no skin on the bottom making it nearly impossible to walk or even stand...and the pain...well, you know all too well. My nails were also pitted and discolored at this point. Basically life was ruled by the condition of my hands and feet on a daily basis.
I have been diagnosed with psoriasis and psoriatic arthritis. My first form of treatment for the skin was topical (dovonex and a steroid). After four months of this regiment, with no results, I stopped and began to seek alternative methods of treatment. I began seeing an herbalist and aroma therapist for skin ease. Some things worked, some did not.
In January of this year, through desperation, I went back to a derm and at that point was put on Enbrel. Unfortunately, I saw no skin improvement on the drug and was removed from it in May, after 3 1/2 months. Though my joint inflammation was combated, which was a releif.
During the course of these health problems, I have also been studying the effects of diet on disease and have changed what I eat with the guidence of a nutritionalist. The inclusion of spirilina (blue-green algae), seaweed and flax seed oils and seeds have made a significant improvement with me in the last 2 months. I have seen my hand almost completely heal and my feet seem to be headed in that direction also. I have paired nutritional additions with doctor prescribed Narrow Band UVB therapy twice a week. The combination has been a life saver...literally!
Another plus to the nutritional supplementation is that spirilina and flaxseed both have anti-inflammatory properties, combating the joint inflammation also. And, fresh juices are very beneficial to the body, healing from the inside out. The liver, in fact, is directly related to skin disorders and when it is not filtering adequately the toxic release can come through the skin. So you may want to look into some detox to rid the body. Also, red meats and animal products are inflammatory and should be limited.
Every "body" is different...so use your best judgement on what feels right to you. The internal healing is slower and difficult to see the benefits right away but I attest to the fact that I have begun to heal and live again...I can hike now with minimum pain and discomfort, a luxury I thought I would never experience again if asked a year ago.
Some of the most helpful readings on healing are listed below, I highly recommend them all in understanding how the body works and heals itself if given the chance. I hope this has been helpful...do not give up hope! Educate and inform your self fully of medications and other ways to combat this sometimes debilitating disease.
"The China Study" T. Colin Campbell
"Healing with Whole Foods" Paul Pitchford
"Family Herbal" Rosemary Gladstar
"Own Your Own Body" Stan D. Malstrom
The best to you, if you have any questions Please ask!
Aurora