Living with Arthritis is something I have been doing for over 20 years and it isnt easy. I have two forms of it and it runs all through my body. The main problem areas are fusing disks in my spine and my knees kill me most of the time.
One problem with this disease is if you use your joints too much it causes severe pain and swelling yet if you dont use them enough it can cause the same thing. There are days you can barely walk but you have to force yourself.
My doctor suggested for every 10 minutes I am on my feet to rest for 20 minutes. When this first started it was hard to adjust to as I have many things that need to be done but with practice I found many things that can be done sitting down such as some of the normal chores of folding laundry, peeling potatoes and so on. I also try and use my sit down time for paying bills, or being on the computer, so it is just a matter of adjusting how you do things.
This in itself does not correct the problem. If you are overweight it is best to lose some which takes some pressure off the legs and makes it a bit easier to move.
Your doctor can also prescribe an an anti-inflamatory drug and pain pills to help a bit more. Knee replacements are possible if it gets that bad.
Some people have luck with applying heat or ice, neither of those work for me but they might for you so no harm in trying.
Several times a day I would recommend sitting down with your legs elevated to keep the swelling down as much as possible.
If you have a lot of problems with walking a cane can give you some support if your legs go weak on you and they even have ones with push down seats so if you are taking a walk and need to rest it is a handy thing to have.
Hopefully some day they will find a cure for this but right now doing some of these simple things and staying in touch with your doctor are the best that can be done.
Dont give up and just sit all day as it will only cause more weakness, try to use the legs and keep them as strong as possible.