Hi Michael,
I have to constantly watch my diet with one eye on constipation, rightly or wrongly I attribute this to the side effects of RT on my bowels.
Mostly I am OK if I avoid too many eggs and cheese, focus instead upon having plenty of cabbage, onions and beans.
It was at it's worse about a year ago, when I was 6-9 months post RT, and had had prostate infections which had to be tackled with antibiotics. I think the antibiotics knock out a lot of beneficial bacteria in the gut.
If you are passing blood which is red, it isn't internal bleeding which would be black, its probably caused by having to force one out.
Whenever it gets too bad I go for the real ale, a few pints of Adnams or Greene King IPA usually restores my innards to rude good health, taken with a meal of cabbage, onions and beans, will usually get things moving.
:)
Dave