HELP! First grow, brown spots, don't know what to do

[realmmlove]

Hi, first of all, sorry for any speech mistakes but i'm not a native english speaker. So this is my first grow, and i really need some HELP ! i'm growing in soil, in about 3 gallons pots (12 liters), 8 thc bomb females. They are 5 to 6 weeks old, soil i think it' a "hot soil" (soil, coco, and perlite) but they grow fine until now. I added nutrients about 2 weeks ago at half strenght (8-4-4 + micronutrients , there' no way to buy cannabis friendly nutrients here ) and made some foliar feeding 5 days ago, 3 ml nutes at 1 L of water. Swithed to 12/ 12 , 2 days ago but i see some discoloration on the leaves and don' know what is that, even i i made a lot of reasearch..
here are some detail and pics :

Lights 900 W HPS( 2× 250 W, 1X 400 W) + 120 CFL (4X30W, 6500 K) to add some blue
12 L OF soil
PH 6.7
Humidity 55-60 %

The problem is especially with one, but i don't want to spread to the others.. please help !

[DW2]

Howdy realmmlove, Your plant look good over all. I do not know what causes those sports, I suspect some sort of microbe. I have had similar spots on my plants during different grows. I have been using Azamax, a plant derived pesticide, to control other bugs. On my current grow, I noticed some similar spots on my leaves and started adding the Azamax into the reservoir (I grow in a DWC setup) and have applied two foliar spray applications as well. The spots have not reappeared (I did trim away some of the heaver spotted leaves) and the plants are doing well.
Good luck with your grow.

[PRIMO]

You made a lot of changes at once, they need time to adjust. Do you water to runoff ? If not ,do so. also I would flush them with a couple of gal of ph.ed water, add Cal-mag and weak nutrients to final jug of flush. Then step away from the plant, leave it alone for a week.

[realmmlove]

Thanks for the answers, meanwhile plants were better after a flush, but now i think i managed to get then intoxicated with nitrogen, even if i use just 1/3 of nutrint strength ( leave tips pointing down). Well i hope that everything will be ok after all..