Hello
As you mentioned that your sister is having only
nausea and all other findings are normal including
endoscopy .
The nausea may be due to these possibilities , these include:
1 Tension or
anxiety or due to pain caused by renal stone , so be aware about that .2 Over eating may be the another reason of such nausea.
3 Hyper acidity or
gastritis . Try raising the head of your sister's bed about 4 inches with blocks . To control stomach acid one should drink alcohol or drinks with caffeine in them or eat chocolates or spicy or greasy foods . Don't eat pizza, burger.
It also might help to avoid eating or drinking for 2-3 hours before she lie down.
As you mentioned that no oral medicine help .
So try these measures and she will get relief.
Also give her some
antacid ( if it contains oxetacaine ,better). As she is having sever nausea , so she may need rabeprazole+itpride combination twice in a day.
Since this is a prescription drug so consult your doctor.
Good luck.