The yellowing you're talking about happens at the very end of flowering right before you're ready to harvest, and it is an even yellowing that occurs. Your ladies are too young for that yellowing to be starting now. Some of your big fan leaves have necrosis. It looks like your lady is suffering from pH lockout mate. I don't think it's the result of nute burn from overfeeding because I don't see any clawing on your new growth.
Without knowing what the pH of your soil is or the pH of the waterings you've been giving her, it will be almost impossible to give you a good recommendation. If possible, I would snag yourself a pH meter to test your water ASAP, as well as a soil pH probe if the funds are available. You can get by with just a pH meter for testing water for now. Hanna is a good brand name that lots of people use on the site. If you're looking into a soil pH probe, I would recommend the Control Wizard Accurate 8.
Don't waste money on any of the cheap pH meters - you get what you pay for. I went through three cheap Rapitest soil pH meters before learning my lesson. They should be the two most important tools of your grow.
:smokebuds: