After doctors complete their training, they usually choose to be tested and certified in certain specialties. Not all good doctors are certified, but those who are have met a standard of competence. A doctor may subsequently choose to become more active in the certification process. For example, FACS means that a surgeon has not only passed his board exam, but is also a Fellow of the American College of Surgeons. To a large degree, these titles are honorary and simply indicate that the practitioner has advanced in his or her specialty.
Doctors incorporate for financial reasons.
My friends and I are in the habit of taking a daily teaspoon of baking soda in a glass of water to relieve heartburn. Ordinary baking soda is a powerful acid-neutralizer and has been consumed for decades for this purpose. It is safe and cheap. However, because it contains sodium, it should be used sparingly by patients who must limit the amount of salt in their diets. I'm a senior citizen in good health.