A Rosehip based drug is the new treatment for arthritis - originally it was only thought to help osteoarthritis but they've found it helps them all. Worth having a look at, I'm thinking of picking some up to try. Painkillers are actually the most important part of the treatment - without them, you hold yourself very wrong and tense a lot with pain, and it makes things much worse. I also take anti-inflammatories from my doctor, which has helped an unbelievable amount (if I don't take them for a few days I can barely move). Unfortunately, with them, I have to take another drug to protect my stomach, but, to me, the benefits are really worth it.
Don't overdo it with exercises, but make sure you do keep the affected areas mobile. You don't even have to stretch them, just either use your other hand to bend and rotate your joints or get someone else to help you.
I see an osteopath to help put my bones back in the right places, but that's partly to do with old injuries and that I have muscle problems too, which steadily pull my joints the wrong way.
As for knitting - it's the best way I've found to learn pacing. I've spent 8 years with this now, and hate the concept of pacing cause I get bored so easily, but knitting's a fantastic training exercise. Do 20 minutes, or even just a row, then put it down for a while. Then go back to it after a break (again, it's what you're up to), and you'll find that taking regular time off means you can knit a lot longer than if you keep thinking 'must finish this bit' etc. If you do that, you'll find after a while that you get days or weeks when you can't knit at all, whereas doing it at a steady pace yields great results. It's crap though, and I'm really sorry that you've got this diagnosis.
Good luck :-)