Unlike candida, there are definitive tests for SIBO. The hydrogen breath test is perhaps the best known. If you haven't already done so, I recommend that you research SIBO and the hydrogen breath test on the web. BTW, it is entirely possble to suffer from both candidasis and SIBO concurrently.
I have experimented with HCI myself. I honestly feel that it is best to have your stomach acid tested before taking HCI. Testing stomach acid isn't rocket science. The stomach contents, after all, are easily accessable through an already existing mouth. For years, doctors eased a thin plastic catheter down the patients esophagus and sucked out a small out of stomach acid to test. Today, with the Heidelberg test, the patient swallows an electonic "pill". The pill measures the PH of the digestive tract as it travels through it, and transmits the results to a receiver outside the patient's body. Cost? About $1000. Plenty of doctors out there would order a full body MRI scan just to confirm a diagnosis for hemmoroids.
There is another test which envolves the patient swallowing a piece of absorbent string. After 15 minutes the string is gently pulled out of the patient. The string is tested with litmus paper to determine the PH of the stomach acid. This test is as accurate as the Heidelberg test. The kit for the string test costs the doctor around $20. Even with the office visit, I would imagine the string test would come in at no more than $250. For $750, I am willing to swallow a piece of string . In fact, if someone offered me $1500 to do it, I would probably swallow two pieces of string.
I am contacting my MD's office to see if he will perform the string test. Will he? Or will he refer me to a GI practice where the $1000 Heidelberg test will doubtlessly be performed. Any bets?