I'm so sorry to hear about your mother having issues after the nissen surgery. I had it myself in 2002 and I had the same issues. Unfortunately, every symptom you described is what was listed as possible complications after having the surgery. I had all those problems too and there was no fixing it. I eventually had gastric
bypass surgery recently and they reversed the nissen because of that, but now I am inpatient once again, for 9 days now, unable to swallow solid foods. It's rediculous. I dont know where you live but I would try to find the biggest hospital around and have her go see a good gastro doc. I'm sorry to say there was nothing they could do to relieve those issues for me myself. Maybe there is a medicine they can offer your mother that will give her some relief. A lot of it gets blamed on diet, so be prepared for them to ask what kind of diet she follows.