I think you are right when you say: It could also be some sort of internal irritation worsened with salt ...
GERD and acid reflux are often an issue with candida. I have come to think taht this is due to calcium deficiency and the lack of calcium in the metabolism to cancel out the digestive enzymes reaction. Well anyhow, try to do a Google search with GERD and see if the symptoms seem right. If so your doctor can give you medication to help with the burning sensation. (and if so baking soda into water will help sooth the burning sensation).