You don't really have that big of a problem, you will never grow a plant that has 100% perfect leaves at all stages of growth, leaves will yellow, die and fall off even if conditions are perfect. Its normal to lose a few. I don't think I have ever grown a plant that didn't have at least a spot or two on a few leaves here or there in veg.
Your problem actually looks to be a small overdose of Nitrogen, overall looking good though.