After reading your symptoms they sound very much like mine, and they are horrible, no one seems to understand the pain that you are in or the way it affects your life and even your personality. It is horrible and i wouldnt wish it on anyone.
Anyway it sounds ike you may possibly have a twisted small bowel due to scar tissue from your c section. I was rushed into hospital twice with horrendous pain and severly distended stomach, after tests it was comfirmed that my small bowel was twisted, fortunately it corrected itself, but i still have the horrible pain and problems eating. Also since then my small bowel has looped twiced, i am now waiting for an operation to correct it hopefully.
The reason why you feel dehydrated is because the small bowel is responsible for delivering nutrients around the body, and if it isnt functioning correctly a person become dehydrated this is also why eating causes problems. I know when my bowel has twisted, so what i do i become nil by mouth and only drink water until the pain eases, also when it twists i cannot got to the toilet to have any bm, again this is because the small bowel has stopped working. This is all i can do until i have my op. I have been off work sick since august 05
You need to get checked out by a doctor who can eliminate a twsited small bowel as it can be dangerous.