Hi, I'm Aliza and I'm a BC patient. I'm also a Medical Librarian (retired), but I keep active in my field by researching for answers and referring people on this site and elsewhere. I didn't have problems with my stomach resulting from BC, so I cannot directly answer your question in terms of yes/no, but I can give you some information from personal experience that you may find helpful.
I suffer from severe IBS. I've had it since I was a teenager (I'm 54. It has some familial or genetic connectionn because my late father had it pretty severely and my brother shows some signs of it.
What's possibly not useless is that a month after my mom's death in August 2011, I had the worst bout of IBS I've ever had in my life. I was tested for Krohn's disease, Ulcerative Colitis, and Celiac disease - all negative. I started dropping weight like drazy. I saw my G.I. Doc had a colonoscopy and ended up on some pretty strong medication (if you want med names, please email me). It took months and a lot of weight came off before things calmed down.
I don't know how chemo affects your gut - only your oncologist or a gastroenterologist can tell you that but I can tell you that severe stress plays a part in the severity of IBS and it was both amazing and awful at the severity of it a month after my mom passed. I was fine during her crisis period (the month she was in a coma in hospice), her funeral, shiva and for 3 weeks afterward. What happened in week 4 is a mystery! The G.I. doc says the stress just caught up with me - the grief. I ran its' course (most unpleasant) and I had a great figure when it finished (while it was ongoing I read a lot watched TV and DVDs, asked my brother to shop for me [we live together]) and occasionally made short forays out when I was feeling brave.
I can suggest things like taking Culturelle, and eating yogurt (I eat soy yogurt) with live cultures-I think the soy tastes better. In terms of food, baked potatos, brown rice, toast, bananas (I'm allergic), stay away from dairy - milk, ice cream, sour cream, cheese (try the soy yogurt), try rice dream instead of milk-get the enriched version. Broiled or roasted chicken (if you take the skin off [whether you get a whole or pieces]), try when you're better seeking out bison instead of beef (grass fed and much lower in fat [don't eat this now-it's too heavy]). But the most important thing I can tell you is to get to a good gastroenterologist (one preferably recommended by your oncologist) who may be familiar with the problems of the aftermath of chemo. I'm sure they've seen this before.
I hope some of my thoughts help you. However it comes about, it's definitely not a fun condition to have and a lot of things are trial and error.
You're free to email me for anything you'd like to know,.
I wish you success in getting a handle on this soon!