@sallylynn you seem to have a lot going on: conditions, medications, tests and specialists. It must be difficult to keep this all sorted out! In most cases a good primary care physician (PCP) can handle these things. The specialists don’t become necessary until a particular condition needs specialized care. I’m sorry you have had trouble finding a satisfactory PCP.

You mentioned having a gastrologist. You must mean a gastroenterologist. This is the specialist for all things stomach and intestines. They are the ones to care for gastroesophageal reflux disease (GERD). They prescribe things like proton pump inhibitors (PPIs) and H2 blockers. Both of these reduce acid, but use different mechanisms. You’ve had experience with both and have mentioned various meds from both types.

You mentioned having an ENT. This is an otolaryngologist or to put it in simpler terms Ear, Nose and Throat doctor. That would be the specialist for your earaches. Not sure if thy could tend to your “Burning Mouth Syndrome” unless it is related to your nose or throat (Those parts of the anatomy are connected after all).

Last but not least your discussion focuses on a concern that past use of PPIs and perhaps H2 Blockers may have caused a decline in kidney function. Two kidney function tests have been discussed here. One is the more common estimated Glomerular Filtration Rate (eGFR) which includes a measure of serum creatinine. The other is a less common, less used Cystatin C test. The basic metabolic panel (BMP) should include the eGFR but not necessarily. My nephrologist orders a renal panel of blood tests and a urine collection that includes more tests. Whichever measurements are used, it is best to get a sense of the trend over time. A nephrologist is the specialist to order these tests and interpret them for you. I must say at this point that I have stage 4 Chronic Kidney Disease (CKD). I did not even have a nephrologist until I was already stage 3 CKD. This is an eGFR in the 30’s. Many general practitioner doctors don’t become concerned about kidney disease until the eGFR gets at least that bad.

As to whether your stomach medications have caused a decline in kidney function your best answer might come from the provider who prescribed them or recommended the over the counter (OTC) medications. If you have difficulty getting any answers there your pharmacist can be very helpful as @collegeprof suggested.