plant health problems mid flowering

[d1pz9]

Hello there guys and gals, I'm new here but I've been scrolling through here for quite a while now looking for some useful info for my first grow.

An issue came up to two of my girls in 4th week of flowering, they are blue cheese clones from an RQS seed, they were healthy through veg and had a small infestation in week 2 of flower with spidermites. After removing the infested fan leaves and spraying the plant with natural mild soap, water and neem oil solution for a week before the buds started forming, the pests seemed to have disappeared.
A week later some weird stuff started happening to the fan leaves, they were starting to get darker in patches, mostly on the outside. Then some started turning yellow a week later.

Now, in week 5 of flowering, most of the fan leaves i either removed or are about to die, they are becoming more yellow quite quickly and some brown spots have started appearing.

I have been searching deep on the web to find out that it could be a number of things, potentially some nutrient deficiencies, but I was fairly confident with the feeding cycles and the amount they were receiving so I was keen to write that off quickly.

It was today that I noticed that the same leaf damage has appeared on a clone (taken from a flowering plant) that's in the same room, which to be fair wasn't very healthy to begin with.
But that had me thinking that it could be some disease that's spreading inside my grow room.

To sum up in questions:
1. What do you guys think this problem could be and how should I approach it?
2. How much can be done to fix this considering the plants are halfway through the flowering period?
3. Could an unhealthy root zone due to the black cheap plastic pots that are potentially too small for the plants (3gal) be causing a nutrient lockout?

Any thoughts and advice are welcome.

PS: sorry for the horrible photos but that's all my shitty phone's camera has got. Apart from the flash disrupting the natural colors of the plant, the yellowing and brownish spots can be seen.

 

[Kampbe1l]

is the clone also in the same area/room?

my first suspect on the list is that neem oil, though it might be irrationally based. the cutting was after you applied neem oil on the motherplant? or, was it not neemed, the clone?

i have no logic other than my past experience with neem oil wasn't pleasant, and i have stayed clear of that stuff.

see if you can first 'quarantine' these affected plants from any other healthy plants - which might be hard. whatever it is, you don't want it to spread to the rest of your garden. careful when tending to plants with suspected disease or pests, keep such 'infestations' contained.

check your soil/grow medium for bugs/pests....

buds are developing well, you're no way near the point of having to harvest early, knock on wood, i mentioned the war.

 

[d1pz9]

is the clone also in the same area/room?

my first suspect on the list is that neem oil, though it might be irrationally based. the cutting was after you applied neem oil on the motherplant? or, was it not neemed, the clone?

i have no logic other than my past experience with neem oil wasn't pleasant, and i have stayed clear of that stuff.

see if you can first 'quarantine' these affected plants from any other healthy plants - which might be hard. whatever it is, you don't want it to spread to the rest of your garden. careful when tending to plants with suspected disease or pests, keep such 'infestations' contained.

check your soil/grow medium for bugs/pests....

buds are developing well, you're no way near the point of having to harvest early, knock on wood, i mentioned the war.

The mother plant from which these two were cloned from (during veg) never got infected and is right at harvest with no issues, yet it was in the same grow room with the rest of them.

These two however, were infected by spider mites at the end of the first week of flowering, that's when I applied the home-made solution. And then like less than a week after I stopped applying the spray, the leaves started turning darker green on the edges of the fan leaves while the rest of the foliage was brighter green. At that point I thought i was overdoing the nitrogen veg nutrients and so i stopped.
Could it be that I have just removed the pests from the foliage because of the soap and the oil that they are now living in the soil and in that way causing disruptions?

Also in the same grow space I am keeping 3 more clones that i took from the same mother plant but in her first week of flower. They never seemed really healthy and had quite a bit of mutations happening but just now I am starting to notice the same yellowing and browning of their first fan leaves.
I'm almost positive now that it's another infestation since it's all over my grow space and all the plants. So quarantining isn't really an option at this point.

Here's two pictures of one of the revegged clones, that one leaf is looking quite bad and I can spot some tiny brown spots on a few other leaves.