ounds like it might be time to find a new doctor as hard as that is to hear. I recently changed Rheumotologists and couldn't be happier that I did. I feel so much more in control than I did before, and also find I'm feeling much better (not really a coincidence -- there's a lot of evidence that supports the link between feeling in control, feeling positive about these diseases [autoimmune] and reduction of symptoms).
As to your labs, they aren't really diagnostic. No labs are. For instance, I'm diagnosed with RA, have a negative ANA, high-normal (but normal) RF, high-normal SED, and the rest of my labs are normal. I've probably had RA for about 15 years, but it had a non-standard presentation until last year.
Having said that, sedimentation rate is a measure of inflammation (systemic). Since IBS is an autoimmune disease that causes inflammation of the bowel, it might be the cause of the elevated sed (normal is <20), but having the joints you describe swollen and painful might indicate a furhter complication like RA, or another form of inflamatory arthritis.
If you are not seeing a rheumotologist, I suggest you do. These diseases are diagnosed by rheumotologist examinations, and your history. Labs and x-rays are viewed more as tools and historical data points than deciding factors.
I hope this helps!