Tried brushing with the peppermint essential oil tonight and it worked like a charm. I have now woken up after a long night's sleep and still have a pink tongue, so it seems to have some staying power.
re: Recurring sore on gums and white tongue... For 2-3 years I have had a recurring sore on my gum that would not go away and plus a lot of white build up on my tongue. towards the end of last year I started using 1 drop of certified organic peppermint oil on my toothbrush that I bought from ebay 1-2 times a day. since then my tongue is pink, no more white buildup and the sore is almost gone. I hope this helps someone out. I really believe the key is using organic peppermint oil.