I used to have this problem for a LONG time. (we're speaking months)
The problem was either of the following:
1. Eating/drinking too many dairy products.
2. Overworking the voice.
3. Using the mouth as a vocal resonator (which is, in enough time, fixed by lesson 2 of singing success... keeping your larynx relaxed is very important).
I hope this helps, let me know how it goes.





I have been having this problem for over a week now. It irritates me.