Those spots appear to be a calcium deficiency. Maybe it's not the cal mag that's causing these issues, but possibly too much of another element that's locking it (calcium last grow, magnesium this grow) out to some degree. Some of the new growth is appearing to have very skinny blades, which would come from too much potassium or phosphorus...with a slim chance it's zinc related. Potassium and calcium are both antagonists to magnesium. Sometimes you only need cal or mag, and adding cal-mag can make a problem worse if the reason one is deficient is because of an excess of the other. I dont have experience watering/feeding that often as i dont grow in strictly coco, but however you do it, she's begging for magnesium. Once the leaves get like that, the deficiency has existed for a couple weeks. In no time, it will go from chlorosis to necrotic. I say add maybe 1/2 teaspoon of epsom salt (to a gallon of water) once in your daily waterings for a few days and see how it reacts.