It is unlikely that the baking soda is causing the symptoms. The ultrasound would be a reasonable step, not only for stones, but to examine the kidneys. The CT scan would be a better test for stones than the ultrasound. I agree that the cystoscopy would be a reasonable next step if the imaging was negative.
If interstitial cystitis is a concern, a potassium sensitivity test would be a reasonable test to consider. This test would evaluate for abnormal permeability and can be considered along with your personal physician.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
Medical Weblog:
kevinmd_b