I searched for others online who were experiencing ongoing foul gas and small stools post colectomy - there were some older posts re using probiotics. I researched that in depth and started eating good pre and probiotics and specifically drink some kefir every day. For me I think the Kefir is making a world of difference and the ongoing diet changes are also significant and contribute to long term health. See the book by Dr David Perlmutter called Brain Maker - he is a neurologist who writes in depth re the microbiome and its possible links to many immune and autoimmune disorders including touching on colon cancer. IF you are wondering why a neurologist is writing about this its because he has studied how the brain is affected by gut health and via this, has come to a firm belief that it affects our entire health along with other emerging research that supports this as well.
I have done some digging on research papers on line and found some that indicate that both the colectomy surgery and the post surgery chemo are detrimental to the microbiome as are the antiobiotics you were likely given. it is essential to get your good flora back. There are some people who have used probiotic enemas to make a big difference and as you may be aware fecal implants are being used for more and more microbiome situations like C-difficile. I am asking my dr this week about the enemas as I want to get my colon back in top notch health. Right now I am finished up chemo and cancer free after stage three so hoping to keep it that way.
If anyone else tries the kefir etc I would be very interested in hearing if it helped you.