last month of flower i need some serious help

im on my 4th week of flower and i noticed some of my leaves have spots on em and are starting to curl up and turn yellow/brown with spots.
need help to identify the problem and solve the problem.

Looks like a ph issue, I'd also look for root aphids....

It is so hard to try and diagnose issues via images on a computer because the images are affected by the monitors profile etc... So go here and look carefully through this:
https://www.rollitup.org/marijuana-plant-problems/559517-have-plant-problem-check-here.html

What's the pH? It has to be right around 6.0.