Hello @jrofri and @marlaxyz,

I'd like to add my welcome, and thank you for sharing very insightful posts on Connect. As Teresa mentioned, there can be a number of causes for shoulder pain. Since you mentioned GERD and hiatal hernia, may I ask if your doctors have ruled out laryngopharyngeal reflux (LPR) or silent reflux? Although the shoulder may seem like an unlikely place to develop pain after eating a meal, most people with silent reflux do not experience heartburn, and have few or no symptoms.

We have several discussions on Connect which you might interest you:
– Laryngo-pharyngeal reflux – made a decision to visit the Mayo Clinic https://connect.mayoclinic.org/discussion/hello-ive-made-a-decision-to-visit-the-mayo-clinic-in-a/
– Laryngopharyngeal Reflux (LRP) – severity and outlook? https://connect.mayoclinic.org/discussion/laryngopharyngeal-reflux-lrp-severity-and-outlook/
–Does surgery work for LPR https://connect.mayoclinic.org/discussion/does-surgery-work-for-lpr/

@marlaxyz, you may be correct in suggesting the possibility of a link between chemotherapy/radiation and arm or shoulder pain; although this study was conducted in breast cancer patients, it may interest you to read about "Treatment Related Impairments in Arm and Shoulder in Patients with Breast Cancer"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4016041/
@jrofri, @marlaxyz are you taking any medications for your GERD? Have you considered alternative methods such as acupuncture or seeing a chiropractor?