Some Help Diagnosing Problem- Drooping leaves and discoloration

Can anyone give me some ideas as to what the problem may be here ::



All the plants are in the same soil and have all been on same nutes, etc.

Now for some reason this one plant has gone down hill the past 3 days.

I held of watering for those 3 days and decided yesterday seeing the soil was dry was to feed it with h20 and some nutes.

I dont know why there would be a deficiency when I fed them aggressively during vegging.

Anyone have ne ideas ?

After some reading Im thinking that its a Nitrogen overdose. Anyone else ?

Anyone got any ideas ? Since the last time I posted about it I have transplanted the plant into a new pot of soil held of watering for 1 day before that and the day after. Have only been feeding it pure h20 so Im not sure whats going on.

Its only about 75 deg. usually in my room along with the exhaust and fresh air intake and fan.

what kinda soil are you using cuz i remember when i used an organic premixed soil my plants hated it so i switched to SUNSHINE MIX #4 and wow they greened up in about a day or 2

Ive been using the black gold coco blend. Been using since germination and I did some research before I bought it anyway. It was a toss between fox farms ocean forest or the black gold figured I try out the black gold.

At first I thought it was over watering so I havent watered it in about 3 days. Then did a big soil/ transplant swap. Im good at transplanting or swapping pots. Got a nice system where the root ball and dirt doesnt even come apart. Anyway even with all that I dont know. Its only this one plant showing symptoms of what ever it is. All the other 10 are still thriving no signs of anything what so ever. I have been watching carefully to make sure.

I had the same thing- Lay off the nutes for a week or three, and ALWAYS check your water's PH before you water,( also, let your soil dry out before watering). I switched from tap water to water from a nearby creek, figuring (correctly, it appears) that it has minerals that the tap water doesn't, Everything turned around after that- Happy Trails / El Indio