HELP!!! Gagging Thick Saliva Post Surgery...Doctors Stumped!!!

My husband was diagnosed with Stomach Cancer (top of the stomach growing into the lower portion of the esophagus). He underwent surgery on Aug. 4th, removing 20% of his lower esophagus-removing the plug "spinter" and removing 20% of his upper portion of his stomach). He was doing quite well at the hospital, was released on Aug. 13th, since returning home, he started not been able to drink...whenever he takes sips, by the 3rd or 4th sip, he'll start gagging and then will regurgitate some saliva/liquid out along with whatever he's drank. He can eat, but if he drinks, then it'll bring back up whatever he's eaten say 2 hours ago. So, on Aug. 29th, he was admitted back to the hospital due to dehydration...since admitted, they did 2 swallow test to see what's happening...and said that everything looks fine anatomically and they also did an endoscopy to dilate the esophagus just incase that's the reason...then, he returned home on Sept. 2nd, and since then he has not been able to keep solid nor liquid down.  He was readmitted to ER on Sept. 16th...

HELP!!! Any suggestions? Did this happen to you, what did you go through and how was it resolved?

I'm thinking that he should ask for some Nexium?

Thanks for reading and all your help!!!