Hello, I saw threads/posts re this with many people puzzled and distressed.  I think the threads have been closed/locked.  I have experienced these symptoms too and I hope this may help some.  Mine started within 2 days of using a strong chemical mouthwash for sensitive teeth for the first time. And greatly decreased slowly after discontinuing its use. My lips also iniially were cracked and blistered after using it.  I believe it is the gel-like detergent- like coating chemical contained within which was the cause.  It's effect seemed to stay around in the mouth for a considerable time and it also seemed to change 'the flora' of the mouth. The lip cracks appeared prior to the change in taste.