Zelnorm side effects

I started taking Zelnorm about a week and 1/2 ago, taking 2 6mg a day and it was to much for me so I cut it down to 1 tablet an hour before dinner and have been doing much better than I have in years, however now the past two nights I go to urinate or whatever and there has been blood not a lot but a little on the tissue. I called the doctor and he thinks it is not related to the Zelnorm but I have been doing a lot of sitting because I am very tired from this medication but it has really helped me. Wondering if anyone else has had this problem. I don't want to stop taking it as I feel better than I have in so long. Not perfect but a lot better.Nancy