Considering the fact that she has Haitus Hernia,she most definetely is suffering from Acid Reflux Desease.
Just so that you know,Haitus Hernia is a condition when due to loose closing of the cardiac sphincter(valve that prevents backflow of stomach contents into the Oesophagus.) which causes the stomach to slightly push into the oesophagus or rather, it causes the stomach contents which are corrossive due to the acidic nature of Gastric juice which is secreted in the stomach to come into contact & corrode the epithelial layer(walls) of the Oesophagus. This explains the searing pain she feels in the upper half of the oesophagus, a condition commonly known as HEARTBURN & if she has been suffering from that condition for a long time then she probably has Oesophagal ulcers( sores or open wounds on the oesophagal walls).
The reason why she gets these pains when she moves around,leans over or Burp is simply because doing any of that causes the acidic contents of the stomach to enter the Oesophagus thus either corroding it or the alredy existing sores/wounds(ulcers) a very painfull thing to go through indeed.
The bad breath is most likely due due bacterial activity going on in the Oesophagal ulcers & or stomach so obviously neither brusfing,flossing nor mouth wash will remove that
The upper ubdominal pain she gets after eating or staying a long periods without eating might mean that she is also suffering from Hyperacidity which causes Gastric ulcers which tend to be painfull after eating since eating involuntarily stimulates the stomach to produce Gastric juice which as I said earlier,is acidic in nature thus corrosive to the abdominal walls
Staying long periods of time without eating worsens her situation since Gastric juice produced in the stomach acts on the abdominal walls & corrodes them since there’s no food to act upon.
The pains she gets have been increasing over the past several weeks probably due to the fact that the surface area of the Oesophagus & stomach epithelium that has been corroded has increased ie the affected area has increased & so has the pain.

WHAT TO DO;
1. You should both make sure that you try your level best to make sure that she is not in stress since stress causes the stomach to secrete gastric juice which in her case, worsens her situation.
2. She should be very carefull in watching her diet. She should cut down her Starch,fat & Protein intake since these require more acid to be digested which will worsen her situation.
She should also avoid Acidic fruits such as citrus fruits & pineapples.She should also avoid pateurised foods & yoghurt
3. She should consider seing a doctor for further checkup to asses the extent of her complication since in Chronic stages surgery is innevitable to cure this complication. If her case is not very serious then she should probably start on Acid depressant drugs(antiacids) as prescribed by th Dr. **Fresh milk, vegetables Bananas,pawpaws,avocadoes & selected other fruits are good natural antiacids so she should consider adding them to her diet.
Ps. Dnt forget to ask the Dr. abt what to do abt the bad breathe
4. Most important; she should consider changing her eating habits from few big meals to smaller frequent meals at regular intervals per day. This reduces the amount of acid produced in the stomach at a time. Note; She should make sure she does not stay long periods without eating,she’s always sopposed to have something(food) in her stomach.
5. She should make sure that meals taken before sleeping should be taken 4 or 3 hours before sleeping( no bedtime snacks) & she should also sleep in the sitting position or with upper body slightly ellevated to avoid sleeping discomfort since this prevents the stomach contents from entering the oesuphagus.
*Curing this complication takes a long time thus requires a lot of patience & self discipline unless otherwise she opts for surgery which is more qucker but costfull & risky.
Hope that helps & she gets well soon.

There are a number of things you could be describing and could be a combination.

A lot of fast food, spicy food, beef and being overweight can make acid reflux worse, especially when eaten late at night. Nexium is usually prescribed by dotors or Prilosec if you do not have prescription coverage.

Bad breath after brushing could be from milk products or other food that gets into little pockets in the tongue or mouth and so need to brush and brush the tongue or use a tongue scraper. Mouth wash can help.

If the pain is getting so bad she is in a lot of pain, she should be checked by dotor to be sure it is not ulers or cancer or something serious. Actually acid reflux can be serious as it is acid fromthe stomach going up and it burns the esophagus and can ut holes in it. Stomach acid is very caustic and can hurt a great deal. Leaning over could force more acid up as it will compress the stomach.

She needs to see a dotor to pinpoint hat the problem is or if there is more than one problem. And to get some medication or treatment.

I have acid reflux but am on nexium and I have sleep apnea and am on a machine with continuous positive airflow down my nose and that kees the acid down.

I hope you convine her to seek a dotor’shelp to get medications or treatment.