the pictures aren't too clear i would take pictures of the whole plant and a lil farther away, but from what it looks like i think it could be over watering. I am still new, but from my experience, that is your problem. I did this too, and i am assuming you haven't been using any nutes, the plant is still too young for them it looks like. let the soil dry out more before you water it again. cannabis tends to do better when it is a lil dryer rather than wetter