Beginner Blue Dream

One of the Blue Dreams is doing really well. Big Leaves and growing fast. His stem is a bit wobbly and because I'm a beginner I dont really know what that means??? One of the blue dreams was slow to germinate and has damaged seedling leaves, he now has yellow spots and starting to have crispy edges??? Trying to research what it is and gave him slightly more water and some more air flow in the greenhouse. Heard it could be a nitrogen deficiency so maybe the biogrow will help. Hoping he recovers. The West Coast O.G. has also been doing well considering he germinated a few days after the other 2. Hes a slightly different color than the others.