Hi there,
This sounds like achalasia, which is failure of the lower esophageal sphincter to relax. The lower esophageal sphincter is a valve that separates the stomach from the
esophagus, and it prevents food and stomach acid from going back into the esophagus from the stomach. Sometimes, the sphincter is too tight and doesn't relax very well, which is called achalasia.
The usual diagnosis for this is something called an upper GI, in which the patients drinks some contrast and then x-rays are taken, and you'll see a pattern like a bird's beak at the lower esophageal sphincter. Another test she should have is manometry, which tests all the pressures throughout the esophagus.
The treatment for achalasia is something called a Heller
Myotomy, where the muscle fibers near the lower esophageal sphincter are cut in order to allow it to relax. This can be done laparoscopically with small
incisions. Some medications can be used, but the best treatment, especially in patients who are healthy and of young age is a Heller Myotomy.
I hope I have answered your questions. Please feel free to contact me if you have any further questions or if you feel I haven't addressed your question adequately.