I'm the one on this board who has been whining about my psoriasis.
But when I was sixteen, I was diagnosed with Systemic Lupus Erythematosis. This caused a severe arthritic condition and complications such as anemia, thyroid disorder, and bronchitis. Long story short, I could barely move. My joints were so inflamed that I could not bend my knees or fingers. I slept 16 hours a day. Had no appetite, so I wasn't eating. I weighed about 90 pounds. Luckily, the disease eventually went into remission.
Bottom line, what helped me work out a lot of the residual joint pain from the calcium build-up was yoga. My yoga teacher was a young guy named Bikram Choudrey (he's pretty famous today and has yoga centers all over the world). Anyway, back then, in the early 70's, he was teaching yoga in Honolulu for my cousin's chiropractor. He really helped me work out the stiff-ness, and allowed me to gain a great deal of flexibility. He seemed to know how much he could push me, and how not to push me. If you could find a Bikram yoga center near you, I think it could help you a lot.
Anyway, for all of you reading these posts. There IS hope. I have been alternately a medical and physical wreck and, at times, in very good condition. After all the problems, I managed to hike Yosemite's Half Dome twice. I scaled Mt. Whitney and back in under 8 hours. I've climbed Mt. Baldy and Mt. San Gorgonio three times, Mt. San Jacinto three times, Grand Canyon bottom and back in about 6 hours, the summits of Modjeska and Santiago peaks numerous times, and thousands and thousands of miles from other loop hikes. I've scuba dived, and done ropes courses. 5K runs. And rock climbing. I'm absolutely no jock, so if I can do these things anyone can. (I'm just no good at skiiing.) I'm not unsympathetic to pain because right now I'm sitting here as my skin is peeling off in sheets. But when I get busy with physical activity is when the pain lightens up.
I guess what I'm saying here is put one foot in front of the other. Walk, hike, run (if you can). And take yoga classes if you can. It's so easy to just FEEL BAD and not want to move around too much. But constant physical motion does help and it can take your mind off the pain. It's the endorphins. Take care y'all.