I think this is a great idea and if it helps your stomach, then carry on doing it. If you think about what you are doing, it is like giving yourself a mini colonic irrigation treatment and these can be very helpful for stomach problems generally.
I had a lot of stomach troubles before Christmas which were causing me severe stomach pains. I found a fantastic naturopath that did colonic irrigation and had a couple of treatments and felt great afterwards. This does go into the colon though, but water in the rectum is just as good to clear that and if it helps you to feel better, then I am all for it.
I have regular colonics and feel a lot better for it and combined with other forms of alternative treatment, my stomach is now better than it has been in a long time.