Excessive watery discharge very unusual, usually very dry right before menstruation, negative pregnancy test period due in next day or so, ?

Many possibilities: Vaginal discharge will change throughout the menstrual. On the other hand, it can indicate infection. Vaginal odor can be a sign of bacterial vaginosis. Vaginal itching can be a sign of a yeast infection. Sometimes vaginal discharge can be a sign of a sexual transmitted infection. It is a good idea to get checked out.

See below: Even with negative pregnancy test, pregnancy is still a possibility. Home tests become possible when you are about a week late.