@jasmine98 , I can relate. While I suspect mine came on due to either the anti fungal med or a combination of that with an antibiotic I took the same day, I can’t be certain.

There are other theories.

I have tried to look at the phenomenon logically. I have never seen any evidence that the constant bad taste was due to dryness or any kind of indigestion in me. It’s something that is on the inside of the body that causes it, imo and so rinses, lozenges, etc. just mask it.

Also, I’m not sure what Gabapentin is supposed to do. I know many people who take it for neuropathy pain and burning. If it helps, then I say great. I tried it and it had no impact on my metallic taste. It made me feel very nice though. Some believe taste disorder is related to anxiety/depression.

There is also a theory that the constant metallic or bitter taste is a FORM of burning mouth syndrome. I have no idea if that’s true but accept it as a reasonable explanation. I suspect that the doctors don’t concern themselves with figuring out the cause, since they don’t know of any treatment. They can’t fix it, so why spend time searching for the cause? That’s my take on it.

This link has a lot of info. So even though it’s called Burning Mouth, it’s an umbrella term for taste disorders.

Additionally: I have had several phantom smells that appeared intermittently for the last 20 years. The last one also happened about the same time my metallic taste started. I lost almost all smell, except for the phantom smell of a floral sweet odor. It lasted about 6 months and left. It just adds to the mystery.
https://www.mayoclinic.org/diseases-conditions/burning-mouth-syndrome/symptoms-causes/syc-20350911