Oh stay away from chemical fertilizers, they are getting less and less popular because they are harsh and effect the taste of your cannabis also. Give your plant a mix of manure, guano, fish emulsion, and seaweed extracts. Or you can buy premixed organic fertilizers also. For a quick shot of nitrogen, dilute some urine in water. 1 part urine to around 10 parts water. This will give your plant a quick does to help it get back into shape.