Damage looks to large to be spider mites. It looks like it was done by a leaf eating insect, possibly a caterpillar or leaf miner. Apply Neem Oil to help fight off pests and only feed plant the nutrient it needs for what its doing. Only apply 20-20-20 for vegging cycle. 10-52-10 should be used for flowering cycle. To prevent over-fertilization try using the moon phases to time your feeding..cycle runs every 7 days.