I too had taste dulling and a mild burning and almost itching sensation. EVERY time it went away after a Nystatin anti-fungal anti-yeast swish. Your symptoms sound very similar especially the "milky coating".

I have mentioned this so many times that everybody is going to be tired of me typing this again but: My Doctors failed to identify the source of the problem because the yeasts didn't show up in the usual visable way. I finally was able to convince my General Practicioner to prescribe something (mostly because he accepted that it wouldn't hurt to try it) and guess what ALL the symptoms went away after about three days of the swish. I now keep a bottle in my kit of tricks because I have had occasions where the symptoms have come back. The number of times have become less and less over time.

I am fairly convinced that many of us continue to suffer needlessly from low grade yeast problems.