I have costrochondritis. In the beginning, I thought I was having a heart attack or a gallbladder attack. After the doctor told me what it was, it made sense. (Seems like if there's an "itis" to be had, we lupies will get it.)
If you even lightly touch any area of my rib cage, front, side, or back, it's extremely painful. I've had to keep from turning around and whoopin' up on people when they unintentionally poke me, and I'm a very non-violent person, lol!
It hurts when I breathe deeply and when I try to lay on my side or stomach. It tends to come in flares, although not necessarily when I feel generally worse, but there is always some degree of tenderness to the touch on my rib cage. Some days I can even feel swelling between my ribs.
Anytime I have a cold or flu or even asthma symptoms, the costrochondritis will flare up. I assume it's because of the workout my rib cage gets with coughing or vomiting.
As far as treatment, a shot of cortisone when the pain is really bad can help, but generally, I just amp up my Darvocet and ibuprofen, and sometimes increase my oral steroids. Moist heat and/or muscle rubs can take the edge off, too.
Hope you find your answer soon!