Well, you probably have lower back or hip pain and will continue to have it unless you get it fixed. The first step here is to get a diagnosis which will mean X-rays, MRIs, and an exam. I have had lower back problems and now have hip problems, and yes, that position can make those areas hurt if they are damaged. Often physical therapy is where you're headed, but you do need to know what is going on before anyone can give you the proper exercises.
Man, oh man. This fall happened 23 years ago?? That's a long time to suffer from such pain! I'm really sorry to hear that. I am wondering about your alignment. I have a son with major major constipation and have this issue sometimes myself. That can be so uncomfortable! My doctor and his (he's a teenager) has us take a stool softener for a couple of nights which helps. My son takes a good probiotic as well. Taking extra liquid can help with constipation (think of your colon like a water slide, you need the water for things to 'slide'). My son has actually been to the hospital a few times for 'impaction' when fecal matter was blocking his color (which becomes a serious thing like any bowel blockage). After the mega enema (gulp), they gave us instructions at home. My son drinks a cup of dark grape juice ever day as recommended by the large Children's hospital ER staff. It definitely helps. He also eats a lot of fresh fruit, helps. So, try some of these things to help with the constipation. Have you tried physical therapy or a chiropractor for your pain?