...forgot to say that if it's thrush (a yeast outbreak) then garlic (if you can stomach that) would help.

Make sure you get enough calcium though... oranges are a good source...as well as sardines (if you can stomach them)... from what you are saying you might be getting low on calcium which hasn't got anything to do with your white tongue issue but will affect you in other ways... you might find that you start getting leg cramps for example... now THAT's something you really dont want believe me!!! A very common thing in pregnancy.