yellowing fan leaves after dry period

Yes the plant abandons those lower leaves. It's all like I don't need those ugly ass leaves anymore I'm making pretty flowers. Lower leaves that get little sunlight turning yellow is normal and actually a good sign in this phase of flower, keyword being lower. The drooping is not good and your plant definitely needs some water. It uses water for circulation and bud development so you really wanna sure it's getting the water it needs. This late in the game I'd strongly consider just a strong Bloom formula with little to no nitro. I'm not exactly sure if that's more pee or poo but I'll let you figure that one out :).