This happened to me from about week 8 till week 15, now 33 weeks and its rare if it happens, just push through, brush your teeth before you eat, and just get in there and do it quickly, and than follow with a quick mouth wash rinse
It happened to me from about 8 weeks until about 12 weeks. I'm 15 now and it doesn't seem to bother me any more. Maybe it'll get better!