Yellow leaves and spots on them, see the pics.

Hey guys, have a little problem with my ak48, one of my plant leaves turned yellow with yellow spots, you can see it in the picture, can anyone help and tell what it is?
My PH is 6.8-7.0 so it can't be Ph burn. Growing under 250W MH on vegitatite period, the light is like 15 cm from the plant, all the time it was something like 10 cm from the light, so it can't be light burn. Using fertilizers, but my mistake was that i used them in every watering, using Cellmax grow mix, can it be a fertilizer burn? Or maybe nitrogen deficiency? Thank you a lot.
Its only few leaves like that.

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I'd suspect nute burn. Could you have splashed nutrient on the leaves? That would handily explain the spots.
cheers 'neer

Oh right, maybe yes, when I watered I could spit some water on leaves.

I would use just water the next few days ... then re-introduce the Cellmax at half the strength. Good luck!
cheers 'neer

Thank you.