Possible Zinc deficiency...?

So I have been looking in my grow guide, all over the Internet and on the sticky posted on the top of this forum, but I am still having a tough time determining what issue I am having right now...I would also like to state this is only my second grow (got EXTREMELY lucky w my first grow as far as not having a single plant health issue, beginner's luck I guess,) and I don't know any other growers nor have I been in any other grow rooms to see other plants, so I have literally only my own very small experience to count on. With that being said, one of my blue dreams is looking really weird, and it all has come about within the last 24 hours or so...I have two other blue dreams, and four other plants that are all doing well. They have all been fed the same, watered the same, etc. My room is kept between 58 and 79 between day and night w humidity kept between 60-70%. The light is a 4' 4 bulb HO T5 23" off of the top of the plants.
The closest guess I have is a zinc deficiency. How was this caused? What can I do to correct it? What can I do to proactively prevent This scenario from reoccurring?
First plant is the problem plant, next two are my healthy induviduals.
Thank you in advance for any help!

Im going to guess over watering

It looks like a bad transplant or some other disturbance to the root system. I like the big foil saucers.

That would be awesome if that is the issue. I kind of thought that at first but I have fed the others identically so I figured if that was the case they'd all be feeling it. I came to the conclusion of the Zinc def because of the tiny leaves w dark veins. I would much prefer the over watering angle though, much easier to fix

Ha those are sweet huh...I needed a way to catch drainage and I figured if I put them in separate things I could test runoff for pH and stuff for each plant individually.

Possible damping off on first one. Lower stem near dirt looks suspicious, but difficult to confirm from photo.