Unable to keep food down after hiatial hernia surgery

My mother is 71 years old and has had a hiatal hernia for years. She was admitted to the hospital after experiencing severe pain and vomiting. Her hernia was so large that her stomach had moved up into her chest and became twisted. She had surgery to pull the stomach back down and a band of some type was used to make the hernia smaller to avoid a repeat. That was 3 weeks ago. She has not been able to keep any food or liquids down since. She even brings water back up. She has had xrays, mri tests and a cat scan. They say all looks normal. The surgeon seems to think that her stomach is not constricting properly due to the fact that her stomach had really been out of place for a long period of time. Almost like when a muscle doesn't work for a long time it becomes weak, that is what he is saying about her stomach. They seem at a loss of what to do. She has already lost a lot of weight and is so weak. She isn't sleeping and is so uncomfortable. I am extremely concerned with her age and her current state of how long she can go on like this. I'm seen alot of other postings of people having similar issues with no apparent explanation. I haven't seen any that have been after surgery though. I am at a loss and worried sick. I can't stand seeing her suffer like this. Any help or advice from anyone would be very much appreciated. I love my mom dearly and need to figure this out.