I'd tend to think it's more likely you had a stomach/intestinal bug. If the nausea was exercise induced, I think it would have happened during or more closely after your workouts. Once you feel "normal" again, I'd get back into your workouts slowly and ramp up. Regular cardio, weight training and stretching is an important part of a healthy lifestyle needed to manage IBD. I'm working out intensely and am in better shape than ever at 42.
Diagnosed with ulcerative colitis spring 1999.
Maintenance dose sulfasalazine. Probiotics, l-glutamine, vitamin D and fish oil caps. George's aloe vera juice. Oregano oil antibiotic, antiviral, antifungal. Mostly grain-free and dairy-free diet. Long-term remission with only minor blips.