Overuse of Listerine

[things]

Early last week I had one canker sore in my mouth, I used Listerine (both with and without alcohol) as it reduces the pain of the sore. I used it rather compulsively, like 7-8 times a day. Later last week, I notice that the white coating at the back of the tongue is thick. I can scrap it off and it looks like old milk.

Is it because of the use of Listerine that somehow change the environment in mouth? Is it because of any other disease?

I have stopped Listerine use now.

[Caliban]

things,
Listerine should not cause candidiasis (yeast infection, thrush). Usually it happens after a serious illness when some heavy antibiotics were used. There are other things which may have caused it: systemic disease, oral contraceptives etc. Candidiasis actually fits the "old milk" description.

As for the sores, Remar gave an excellent suggestion for buying OTC type mouthwash: colgate peroxyl I believe is one of such mouthwashes.

[remar]

It could be because of the Listerine. There is a rinse you can buy at any drug store for canker sores. I'm sorry but, I can't remember the name of it. Ask your pharmacist.
Are you brushing or scraping your tongue before or after brushing? It's something you need to do every day. That could be another reason for the white coating.
One more thing come to mind, thrush. Only your dentist or Dr can say for sure though. If it is that, it's easy to treat.