When you see leaves that are unusually dark, Nitrogen toxicity is the first culprit.
Toxicity of one or more nutrients can also cause lockouts of other nutrients such as Mn as Haze said.
The leaves becoming deformed is another sign that you have a problem.
You really want to FLUSH FLUSH FLUSH!!!
The final flush should be with a complete fertilizer including micronutes, applied at only 1/4-1/2 strength.