First let me say that anytime you have chest pain you should seek medical attention immediately.  That being said, have you been tested for cervical arthritis or have you been told that RA has affected your shoulder.  Both of these condition can cause chest pain.  Also after a short stay in my local ER I learned that RA can affect your chest bone as well and even cause inflammation.  Talk to your rheumatologist and express your concerns about this because he may want to do further testing.  I can tell you that when I have RA pain in my chest it always helps me to take a hot ( but not too hot) towel and place it on my chest for awhile.  Please pursue this issue with you doctor because any chest pain can be very dangerous.  Good luck, and best wishes!