Took a look at the other thread and have gathered some data.
1. Are you using any nutrients? (if so, at what strength & for how long?)
2. What is the ph of your water & your run-off?
3. What are the temps in your room?
4. How far are the lights from your plant?
5. What light schedule is this on? (18/6, 20/4 , 24/0 etc..)?
From a first-look this looks like a Magnesium deficiency accompanied by a Zinc & Phosphorous deficiency.
It could be that you've fed it nutrients and the plant has gone into nute-lockout and isn't getting what it needs, or it could be severe nute-burn. Both, luckily - can be treated.