I would add the extra lights and lower your cobs slowly it's kind of a bad transition from natural light to cobs the plant needs to adjust. Also I would recommend you start using a strict wet/dry cycle letting the soil dry out a bit more than usual it looks like you may be over watering. It's preventing the roots from pulling in nutrients especially nitrogen this why your losing your lower leaves and pale upper leaves. The spider mites probably didn't help much.They may benefit from some additional Calcium and magnesium since these are needed to grow nice buds. Hope this helps you š