Gaffer, one of the guys I met while having RT has recently been suffering from radiation proctitis about 16 months after finishing the RT. It seems to be a hazard, and not fun. I have a few bottom issues, but fortunately they are mostly first thing in the morning (seemingly triggered by going from horizontal to vertical and moving around) which is a time when I am reliably in near proximity to a toilet.
Imodium is a brand name for the drug loperamide, which is widely available over the counter as an anti-diarrhoeal medication.