Brown spots on leaves

Hey so I haven’t had many issues with my first grow but now I’m having brown spots on my leaves my last watering I did up my nutrients from 25% strength to 50% percent strength auto flower northern lights grown in mothers earth and ocean forrest mix iguana bloom juice by advance nutrients is what I’m using my last two waterings I didn’t include extra cal-mag because I thought the mixture had enough please help my lady out lol her sister plant I’m growing next to her wedding cake strain seems to be doing fine...

I guess I can’t get any help thanks

That could be numerous things. Looking at the picture, I'd say dont worry about it. The rest of your leaves look good. Feed with a dose of calmag or a little epsom salt. If the condition worsens, we'll go from there