How far along in flower is she. How many weeks? And how tall.?

Do you keep this plant outside? If so.. Where do you live? And what Strain is she.?

Nutrients/Water.. How often, how much and size of plant container?

There could be a number of contributing factors, could be a slat build up (Nutrient Lock-out), It could be lack of nutrient/s. Those are my first 2 starting points.

Ill need more info on her to help you out. In the mean time, check these FAQ's: Text and Text

These should help a lot.

Good Luck,
TPJ