i uderstand what you mean. the water intake improves the motility of your colon, and then you actualy get to feel the urge to go, but with the prolapse it's absolutely impossible to get ANYTHING out!!!! (i know how frustrating this is, blieve me).
though for me, increasing the water intake didn't help at all. i had the urge only with laxatives, but couldn't get anything out, even with lots of laxatives. at least now, after the STARR, the laxatives can help me.
i also had my prolapse for over 10 yrs. and as far as i know, the longer time you neglect it, the more damage to your digestive system. please get help fast.
i really really hope that your only magor problem is the prolapse and NOT the colon and after you fix that, you won't have any problems to go. did you have the sitz marker test yet?
after you get to fix that, you have to start eating right, you know: 3 liter of water, fiber and lots of foods that improves the motility of the colon. one amazing food that really helps is beetroot!!!! you might want to try one bowl of scraped beetroot every evening. it really do wonders. it has lots of fiber in it too. but, again, with CI it won't help.
many blessings to you, and keep us posted, ok?