Robertblanch1, Colleen's recommend re colorectal cancer, sounds like it might have a benefit..maybe try the Cologuard( the one in the box) first. Diarrhea for years, due to SSRIs, sounds awful. What changed to cause such a radical shift from yrs of D, to constipation and dr.s view that you had severe constipation or a mass? That seems like an enormous swing. What type of dr. jumped to such a drastic , and apparently wrong conclusion? Do you have other health problems? I understand the multiple prep for CT, you are a very smart cookie. 17 yrs of CIC, under treatment of GI(general idiot-is how I feel about the dr.) last year I had 2 X-rays, 2 months apart, both read by the radiologists as " probable formation of small bowel partial obstruction. The GI, disagreed and ordered a CT w/contrast ) in 3 weeks. I was so afraid of the 💩💩‼️‼️pain that I ate as little solid food as possible, drank meal replacement protein shakes, lots and lots of water, enough miralax to keep my poop from thin mush to diarrhea. Well, good and bad. I cleared my colon so well that the CT showed no signs of obstruction of any kind, just mushy poop. The bad part was I started eating some more food, still heavy on miralax, cuz after the "clean out " my colon, small and large, jammed up pretty fast. 3 months later I was in ER via ambulance, 3 days in ICU with a nasal gastric tube up my nose and down into my small intestine. A few days home, too tired to take the miralax and 💩💩. The problem of not being able to bear down is real and not fun. Part of my smooth muscle action, needed to poop, is Hyperparathyroidism and elevated calcium. Elevated calcium is not good for smooth muscles. I am not saying you have this, it's just one of a billion reasons for 💩problems. Don't know why, but women have this a lot more than men. But, that doesn't mean men don't have it. Possibly get your PTH, calcium, vitamin D, ionized calcium tested. You can't get a diagnosis off 1 set of tests, you have to have results to be useful. I f you choose to look at HyperPARATHYROID.com and/or swparathyroid.com, both are very reliable sources for diagnosis and symptoms. Do you have a lot of the symptoms listed? But, there's lots of other problems with many of the symptoms. Best heartfelt prayers for your comfort. Shelley