Yellow/brown spots on leaves

Hi,

These spots started to appear on the leaves recently. Any ideas on what's causing this?

Any help appreciated,

Thanks

We need you to provide info about your grow.

Sure. The strain is biscotti. It's under 125W light in a 2*2 inch tent. Medium is soil. She germinated about 7 weeks ago.

I gave only water until last week since then I fed her twice with fertilizer (Bioniva soil supermix main fertelizer NPK 7-3-6 ) said on the box to mix 26 ml fertilizer for 10liters of water. She drinks about 1.2 liters.

So first time i mixed 1 ml and second time 2 ml of fertilizer for my 1 liter of water.
After first time i spotted a few spots here and there but after the last time (2 days ago) i see it's spreading. She looks great other than the brown spots.