start checking ur ph lvls, its a must...if the ph is to high or even to low u will cause nutrient lock out. ur showing nute deficiencies, but dont just go and add nutes. mix ur water and ur nutes and then adjust ur ph, even though ur in flowering stage ur plants are lacking nitrogen, add some extra nitrogen, but keep ur phosphorus a lil higher...i went and searched ur problem in my cannabis grow bible so this info is pretty much dead on