It seems to me he's not ferting enough,and there's not enough info to give a good answer.What size pots are you flowering in?Did you start in a smaller pot and transplanted up twice?It sounds to me like you have a massive magnesium defeciency to me,are you using tapwater?Is it hard water?Too much calcium locks out magnesium which is sorely needed.As for feeding I feed every time I water.My flowering plants are fed every third day in 3 gallon pts,say twice a week.I use 2 teaspoons tiger bloom PH'd of course.The next time its 2 teaspoons tiger bloom and 2 teaspoons liquid Karma.Next watering its 2 teaspoons tiger bloom and a tablespoon of blackstrap molasses.Then it starts all over again with just 2 teaspoons of tiger bloom.In veg after the plants are a couple inches tall I feed 1 teaspoon Pure blend pro.When they are about 6 inches tall I use a tablespoon of PBP every single time I water,I feed.People are always talking about overferting,using quarter strength and such,I dont subscribe to that technique because feeding each and every time works great for me.I flower with 1K horties and I never have a plant that doesnt yield at least a quarter pound with an average yielding strain like blockhead.You sound magnesium defecient though and if you're using hard tapwater you certainly are.Shit it took my dogs water bowl to become calcified on the surface before it hit me and I started using R/O water.The difference is night and day