What Causes Terrible Pains On Both Sides Of Hip Area Post Horse Riding?

I rode a horse yesterday very hard (not by choice had to keep up and this horse had a terrible hard trot). I kept banging into the saddle very hard for quite a while. I have had a lot of intestinal surgeries from colon cancer and today I have terrible pains on both sides above my hip bones. Can you bruise your kidneys or something else after taking such a beating - which it was.