3 weeks into flower BIG PROBLEMS, please help

can any one tell me whats going on based on these pictures ?

you will get this happening in flowering stage which is fine. Looks like N deficency, Possible P and Mag deficency. This is common. Next time watch for when they start to turn a light green and add cal-mag to feeding and it wont go as far as it did this time. Looks like you had nute burn also

Also why did you take those leaves off? you didnt think the plant needed them?