I have IBS C as well. Since it got really intense, about a 1.5 years ago, my fatigue has gotten way worse. I quit caffeine and almost felt like I had no energy for about a month or two.
I've been on a Low FODMAP diet and try to get as much sleep as I can. My energy has started to return, but I'm often still very tired. Anxiety has always played a large role in my life and I'm trying my best to minimize and manage stress and anxiety now.
Becky, I will try those Yoga poses. I do enjoy doing Yoga.