I was diagnosed with IC in 2008. I had chronic UTIs, and then after medication cleared the UTI I had horrible rebound pain from the IC, which I thought was the UTI coming back.
In fact, IC causes dead white cells to appear in the urine (from the injured lining of the bladder) and looks like a UTI on simple tests.
The PAIN of IC when it is flaring is terrible. Heating pads help. And I have found that the best way to eliminate the pain of IC is to exercise very mildly in a warm pool....a therapeutic pool which can be found in most health related fitness centers. (not the kind with lots of young people in spandex).
To eliminate UTIs I take one capsule of D-Mannose daily. I haven't had a UTI for four years (after chronic infections). I 'thought' I had a UTI last week, which shocked me, but it turned out to be my IC flaring. Which it hadn't done for four years.
I wish for you the best of luck in taming your IC. The relationship between IC and Sjogren's is very close, as you know.