Plant is 61 days old 2nd day of flowering. Medium is build a soil 3.0. Watering at 6.4 to 6.5 running a gorilla zkittlez with hlg135watt quantum board. Problems started when I wasn’t watering near enough letting the medium dry out too much. Was dried out and turning yellow after watering problems fixed the plant is still yellowing and hasn’t ever looked as green and healthy as it once was.
Need help diagnosing before this gets worse
Just looks a little nitrogen hungry nothing serious
I agree start with a half dose of nutes at most. Maybe even 1/4 strength and wait for the plant to respond. If not a healthier color in a week give some more N.
@bengaltiger81 agreed with statement above. Looks hungry hit with a feed of N. Dont let dry out to much keep somewhat moist but on dryer side. Also is ever going some where makes sure to water thoroughly enough to not dry out for the amount time leaving. Usually no more then four to 5 days then plant will need a drink. Happy growing gl growmie. @Ironman26 also good statement. Tons of knowledge around the board nice to see. 
plants will start to eat or “cannibalize self”
Could also be magnesium deficiency. Also see some leaf tips clawing left and right, this could indicate something up with the ph, although I’m not familiar with build a soil 3.0 so not sure what ph should be exactly (6.5 maybe), if you can test runoff ph just to make sure your in range then you can cross that off your list of potential problems . Also some new growth looks deformed, which again could be something up with ph
Anyway not saying I’m right just wanted to give a little more insight. 
This looks like magnesium to me
Thank you
