My knee cap is starting to hurt? I work all day standing and I have RA?

See your Rheumatolog. Pain in the knee cap could be related to RA however there are other possible causes. For young women especially there is a problem called chondromalacia. There are also other types of arthritis, and functional problems and bone abnormalities related to your disease. You should discuss your symptoms with your rheumatologist and determine a cause before any other steps are taken.