What to do for an elderly person who is obsessed with having a bowel movement?

My mother has been with me for 2 and 1/2 years. In the past she has felt like something was wrong if she didn't have a big bowel movement every day. She recently just spent a 2 month stent in rehab. Now the bowel movement is all the time. She is bed ridden right now, so I figure part of the issue is her immobility. Her stools are not hard, but she says she is constipated all the time. She'll be laying there just yelling like she is in the most awful pain. She'll call me to check her because she thinks she did something but is not sure. Most of the time there is nothing. I bet I went to check her about 5 times today within just a few hour span. It's driving me crazy. She did this in the nursing home, but they assured us she was not constipated. Her bowels were active and they checked her rectally and she was clean, but she insists she's got to have a bowel movement. Any thoughts on this.