classic "N" nitrogen toxicity (to much) presents it's self as dark green colored leaves and also the leaves look like a "claw", this is a common issue, Just flush for one week:" Remember once you see a problem you are all ready two weeks behind in fixing it" - if in flower stage the plant does not need much "N" at all Hope this helps!!!!
Stop "N" use and increase "P" & "K" ( "P" being in greater amounts of "K" and "N" should be lower than "P") plant need "P" for flower development and "N" for vegation growth