Constipation - has anyone ever had a similar experience/have any expert advice?

You may have colitis. An infection in the bowel or lower intestinal tract. When the same thing happened to me we tried every laxative known to man.... nothing worked or it worked too much. I started eating plain vanilla yogurt. Every day - 3 times a day. Something about the bacteria in the yogurt worked for me. I found that seeing a gastrointestinal doctor as opposed to a general physician made more sense for me. Good luck!