You don't have to tell your doctor anything. However, in order for him to treat you as best as he can, you should. You don't, however, have to increase the pred if you can't live with the side effects. There might be another medication you can try.
Symptoms began in November 2008, ~4 weeks after giving birth to my son.
Eased for ~3 weeks in December, possibly b/c of probiotic use?
Returned in January 2009 (with a vengeance), diagnosed with pancolitis on January 30.
Currently taking Asacol (400mg 4 pills 3x daily), Rowasa nightly,
40mg 30mg 20mg 15mg 10mg 10mg of Prednisone every other day, Culturelle probiotic, and Zoloft (25 mg).