Hi Frogga,
I also have the baking soda-metal taste. Like you, I am not one any anti-epileptics meds.

About a year ago. I had some of my mercury fillings taken out, thinking it could be part of the problem.

I have had cultures because of this horrid SX. But nothing came up positive. But I could of been tested for the wrong thing. Maybe you could have a throat culture and possiably a culture as well on the back of your tongue.

What I eat is very healthy. I also drinks alot of juices. Until the root of this problem is solved. Hugs, Roz xxx