I have had the same problem for over a year and like you, I cannot get an answer as to what is causing it. I have had Sjogrens for years even though my blood work is negative. I have dry eyes, dry mouth, dry skin, etc. The taste started out slowly, being salty just a few times a month and now it's either a salty taste or a sour taste everyday. I have seen a dentist, an ENT and a Rheumatologist, had a brain scan and tried the two saliva increasing medications but nothing has shown up on the tests and the medications didn't help so I stopped them. The Rheumatologist thinks it's neurological but gabapentin and duloxetine have not helped either. I can taste food and that's about the only time I can mask the bad taste but as soon as I'm done eating I have to chew a piece of gum to mask the horrible taste that starts again. Anything really salty is off limits and even chocolate is not pleasant anymore. I'm really ready to give up with doctors but I have a neurology appointment in the spring that I'll keep. The taste centers in teaching hospitals seem to cater to the post Covid patients who had a complete loss of taste and smell but I may try calling to see what they say..... I have interacted with two or three people who have a similar issue but no one has found a solution. Keep in touch.