https://community.yinyanghouse.com/t/hiccup...is-press/2144/2My guess is that while you are massaging around the shoulder you may be hitting the vagus nerve or the pressure of the massage may be influencing the vagus nerve
The following from wikipedia explain the very broad functions of the vagus nerve - which is why we focus on opening that area in many different conditions:
The vagus nerve supplies motor parasympathetic fibers to all the organs except the suprarenal (adrenal) glands, from the neck down to the second segment of the transverse colon. The vagus also controls a few skeletal muscles, namely:
* Cricothyroid muscle
* Levator veli palatini muscle
* Salpingopharyngeus muscle
* Palatoglossus muscle
* Palatopharyngeus muscle
* Superior, middle and inferior pharyngeal constrictors
* Muscles of the larynx (speech).
This means that the vagus nerve is responsible for such varied tasks as heart rate, gastrointestinal peristalsis, sweating, and quite a few muscle movements in the mouth, including speech (via the recurrent laryngeal nerve) and keeping the larynx open for breathing. It also receives some sensation from the outer ear, via the Auricular branch (also known as Alderman's nerve) and part of the meninges.