Can anyone identify this problem?

Hello everyone my plants have been doing pretty good so far with no major issues. I've been using very little fertilizer and was wondering if this may be causing my problem? I will attach some photos. Thanks for any help or info

the choices are:
1) you're spraying the plants with something you shouldn't,
2) you have bugs eating the leaves,
3) you have a nutrient deficiency, like magnesium as this really resembles magnesium deficiency, so I'm going with that.
If that's it, you can solve this problem by getting some Epsom salt, put one level teaspoon in a gallon of water and give that. It will be a day or two before you see improvement, if I'm right about this.
Other than these possibilities, I have no clue what it could be. I suggest that you consider trying a more well-rounded fert and when you have problems, please put up more info, like what kind of fert you're using, how much of it, how often, air temps, etc.

Thanks bud! They are outdoor plants In a Well vented greenhouse. I have sprayed some cedar oil but didn't think I hit any leaves. There were a few leaf hoppers in there that's why I sprayed the cedar... The spotting is only on two out of three plants which are both different strains. Using Promix bx and just started using neptunes harvest hydrolyzed fish fertilizer npk of 2-3-1.

I'm only using half of the nutes I should be as well so I will try to up the nute intake over the next couple weeks

don't force your plants. doing so can create over fert damage. consider what I said about the Epsom salt. if it's mag def, then that should help. it's best to use a well-rounded fert, but don't over do it.