To the OP. I see you mention gastroentrology in one of your posts. If that is important to you, Sriphat has a specialist gastroenterology unit, in the Centre of Medical Excellence Clinic, that has an endoscopy unit attached. Many of the doctors are on the staff of the CMU medical school. I have been going there (more regularly than I would wish!) for years
I can confirm Folk Guitar's comment that Sriphat are usually as cheap as, and sometimes cheaper than, thee average pharmacy.
The Gastroenterology unit is here:
https://goo.gl/maps/hY65ixpJokznQK69A