Yellow interlinked spots on leaves -nitrogen deficiency? (flowering)

[N.B.B.]

Hi all!

I'm on my 6-7th week of flowering and a few weeks ago yellow spots began to appear on a few of the bigger leaves. I'm gonna chop the ladies soon so I flushed 5-6 days ago and the yellow-spotting is getting worst, so my hunch is that it's gotta do w nitrogen.

I'm growing Master Kush in coco in air pots. I was feeding the ladies AN nutes, AN bud candy and a 3rd generic nute w high N, CA and MG content. They're only being fed sucanat now.
EC was between 2.5k - 3k.
The light source (600w HPS) is approx 1 foot above the tops of the plants. I don't believe it's heat stress, because it isn't the uppermost leaves showing these symptoms (but I could be wrong).

I'm close to harvest so I'm not too worried about this, but for future reference could you guys (and gals) spare me your 2 pence on what u think this is.

If it is nitrogen def then y isn't the complete surface area of the leaf affected? Y is it yellowing in this pattern?

Pics below.

Any help appreciated!

 

[JJ Bones]

What is the pH?

 

[N.B.B.]

If u think that might be PH then u may b onto something.

The AN Big Bud (confused it w Bud Candy sry) could have thrown my ph off.. it took me a few waterings to realize its acidic and since my ph meter is broken now it is possible that the sucanat is off too.

JJ Bones does this definitely look like a ph issue?
The weird part is it's only one of the plants doing this even though they r fed the same nutes.