No BM for two weeks

Hi! My mother is 79 and has used laxatives and enemas most of her life. She can go up to two weeks or more without a BM. She has no pain, no cramps, no other symptoms. She has had Xrays done before. Sometimes there was stool in her bowels, sometimes not. Yet, she obsesses and worries after a week with no BM. I know it does sound serious, but she has never been sick from this. Any suggestions as to what this could be, or how to tell her to quit taking laxatives and enemas?!!!