GERD after Bowel Resection

Five weeks ago I had 18 inches of my sigmoid colon removed by laparoscopically due to repeated bouts of diverticulitis.  Four weeks post op I came down with a severe case of heartburn. Since I was still not eating "normal" foods I was totally surprised at the severity of heartburn. Prior to the resection I have never had GERD/Acid Reflux/hearburn.  

I called my surgeon who referred me back to my GI doctor.  I asked both doctors if the heartburn could be related to the surgery as again I have never had this prior.  Both said they did not believe there was a correlation to the hearburn and resection.   The GI doctor put me on Aciphex for 6 days which did not work and put me on Nexium 40 mg twice daily yesterday which does not seem to be working either as I have to take rolaids about 5 hours after taking the Nexium.

Can you tell me:  

1.  Have you ever heard of hearburn/GERD starting after a bowel resection
2.  Why isn't a PPI, at this strength, supressing the acid