You know that taste you have in your mouth after you drink a glass of milk? Well for several days I have had that taste in my mouth, whether or not I have had milk. I just brushed my teeth. I have not drunk any milk today, although I had yogurt at lunchtime.
Have you ever heard of this?
Surefire symptom of Bubonic Plague. Make sure your life insurance is up do date.
Could be a bit of acid reflux, or a thin film of bacteria on your tongue. Try an antacid. Maybe pick up one of those tongue-scrapers. I got one and I find they make a big difference - moreso than brushing your tongue.
Do you find your mouth is dry? I have problems with dry mouth and often have a sour taste in my mouth, because the bacteria can’t get flushed away properly by saliva. Drinking water doesn’t help. I have a spray for dry mouth that my dentist gave me that seems to help a bit.