The next question is, "if I have low stomach acid, why". It's normal to lose some gastric acidity as you age. But I'm betting on Helicobater Pylori. Low acid causes mineral deficiencies, which in turn could cause functional hypothyroidism. Low acid allows bacteria and undigested food into the intestines, which in turn could cause candidasis and/or SIBO.
We're up to a four Antibiotic "cocktail" to cure H. Pylori in many cases. Sound like it can't be cured in about 20% of cases. By age 50, over fifty per cent of the population is infected with H. Pylori. We don't even know how it is spread, and it's becoming increasingly drug resistent. This bacteria is real bad ju-ju.