Mary I'm not very clued up on your condition but my 3 year old has severe eczema and I know finding the right treatment is a long and painful road but I would assume the two conditions are a little similar? Here's some of the things I have tried with him, maybe you will find some comfort in trying some:
Oilatum for the bath: Tried quite a few bath treatments and this one was the best for him.
Oat baths: Thanks to some of the FMS back over at C4 I was told about oat baths. Fill a cotton sock (or something that the water can seep out of) with oats and let it bob around in teh bath while you're running it. Then use it as a washcloth. This always calms down the redness on my son's skin and has a good soothing effect on his behaviour.
Anti-allergy begging: Might be a bit costly but it's worth it IMO. Washing your clothes ina non-bio liquid and then giving them another wash with no detergent is a good idea to make sure there's no residue to irritate your skin.
A daily anti-histamine: Supposed to help with the itching but it didn't really do my son any good. But seeing as you're older you will be better at deciding how well it's working and can try different strengths.
Doublebase/Dibrobase: My son hates these creams...they seem to heat up his skin and cause him real discomfort so we tried a few oterh ones and the one he seems most settled with is Cetraben. It's just a moisturiser so I guess it's suitable for both conditions.
There are loads of things we've tried but I can't seem to thing of anything else at the minute
But on our visits to the hospital for treatment I am forever being told how well the Sunbed treatment works for people with Psoriasis (sp). We've met so many people who swear by it so maybe you could ask your doc for a referal to the dermatology departmetn and ask them to consider you for it if you haven't already tried it. It's probably one of those things that works for some and not for others though which is usually the way with these things
Oh and it's not called the Sunbed Treatment but I don't actually know the real name of it