Chemical taste and yellow tongue after tooth extraction

I recently had my left back tooth removed a month ago due to failed root canals. The tooth in front of the extracted tooth was cold sensitive right away which I was told was normal. However, in the last week I have developed a HORRIBLE taste in my mouth that tastes soap or like chemicals. I also have a yellow film on the back of my tongue. I swear the taste is coming from this other tooth but it is no longer cold sensitive and my dentist wont' see me for a week. Anyone else experience anything like this or have any idea what would be causing this?

I've been told this could be a sinus or liver problem, due to the yellow tongue and an upset stomach but I had total normal blood work a month ago at the doctor. I can't help but feel it's this other tooth since the gums are sore above it. I also have a small pimple above the extracted gum.

PLEASE PLEASE any help is appreciated!

[scottma]

Stain of the tongue is generally exogenous and may come from food, cigarette, chromogenic bacteria, and mouth rinse containing peroxide. Going back to your surgeon to have a follow-up exam is advised.