constiptation again after 5months operation

i am writing this for my wife, she is 28 and we have our first baby on may 5th 2012, and it was a normal delivery after the delivery her stomach start to expand with in no time and  start  a type of yellow  colour  precipitation coming from her mouth
Doctor asked to take a ct scan to and find that there a 2 or 3 small scratch in large intestine, and take her for an emergency operation the operation last fro more than 6 hrs, and the findings was her rectum was blocked and due to that stool start accumulate in the intestine and the intestine becomes very thin in some parts due to that  scratch in her intestine. she visited the same doctor at her 7 Th month of pregnancy due to pain in the stomach and she had taken a n x-ray that ime and found a bulging in stomach and the doctor assume that it may a tumor that can be removed by the time of delivery if in case ofa Cesarian .

After the intestine operation doctors removed a large portion  of large intestine which is infected and sent that fro the biopsy test for the result. after the operation a stoma inserted on the right side and a colostomy bag outside for the stool discharge . after 2 weak undergone 2 nd operation  to fix that stoma and a bag permanent in to her body. all went smooth up to five months after the operation but for last five  no output from her or even discharging gas  , she consulted the doctor and he is surprised for this situation on her last visit to doctor every thins was fine.

what to do in this situation and i am afraid of chance of bag to break and if what can we take the precaution for this.

And what kind of diet she need to flow.

Regards

sudeer.