We would need a lot more information in order to properly diagnose:
What strain is it?
How long has it been in Veg?
Indoor or outdoor?
Soil, Soilless or Hydro?
If soil/soilless, what is in your mix?
If soil/soilless, what size pot?
Size of grow space (LxWxH)?
Make and model of grow light?
Temperature in the environment?
Humidity in the environment?
PH of medium or reservoir?
PPM of medium or reservoir?
How often are you watering?
Type and strength of nutrients used?