It's still a bit early for yellowing, hmm seems like there should be enough N between the feeding and the soil. How's your soil pH? If you're on Bloom nutes, next feeding you could try half Grow nute and half Bloom nute in the water for one or two feedings. That'll give it a little bit more N. The yellow leaves won't go back to green, but what you want to happen is to arrest or slow down additional yellowing. It'll come back strong again close to harvest but that's okay then.