Help with sick plant please!!!

Hello I'm having trouble figuring out what is wrong with one of my plants. The leaves are kinda like rippled or curled. I'm thinking maybe wind burn, too much nutes or a ph problem? The plant is an Ak47 autoflower in 100% canna bagged coco. It's in a 4x4 tent under a 600w mh dimmed to 75%. Im using 1 16" oscillating fan so I wouldn't think it's wind burn but who knows. If you need any more info or pics let me know. What should I do to correct the problem as fast as possible? Thanks for looking!