You should probably post this in the problem plant forum. There is a sticky there on everything yo should post with it, like nutrient and lights. Other than that, can't really help yah with no information.

Also, a good resource are these two sites: Grow Marijuana FAQ, Cannabis cultivation - marijuana growing tips & photos
Revised: The Complete Guide To Sick Plants,pH and Pest Troubles - PlanetGanja.com

It has pictures and descriptions of plant problems from the most common to the most off the wall. Read up and good luck!