bowel problems after hemicolectomy

Two and a half years ago I had a right hemicolectomy for bowel cancer. I was given the all clear and have been having 6 monthly check ups. About 3 months after the op I had a horrid bout of dhiahoea (cant spell) which came back a few weeks later and over the next 2 years has got worse, happening almost every day, The g p prescribed mebeverine for the cramps and I was ok for a while but it returned and I find that if I take immodium as well, I get very constipated. I try to take the drugs when I am going out and try not to eat before I go out. I always have to suss out a loo when I'm out. I work outside so I find sometimes I don't eat all day. has anyone else had this problem. I am awaiting my routine blood tests and am thinking that maybe the cancer has come back but the docs say there is no reason to suppose that. I am concerned because I was ok immediately after the treatment and it is getting worse. I also have nerve damage from chemo. I m grateful for any advice