Since I have 90 minute sessions and I have a tendency to need the bathroom due to nervousness, too, my T knows I have to go. It's been pee, not poop, but I used to have IBS very bad so there's always that possibility. I eat lightly before my session. Try banana or rice. I tell my T my stomach hurts, too. She's always asking where in my body I feel something, which I hate talking about, but it makes it easier to say when I have to use the bathroom. Only problem is that it's out the door and down the hall, and I hate to waste the time. But if you have to go, you have to go. T would understand! I also suggest taking Pepto or something ahead of time. I used to do that before parties and stuff, and still keep it with me!