What are these Tian Tsin leaves showing symptoms of?

I've sprouted entirely too many pepper seeds/seedlings for my newbie year... and it's the ONE plant I kept alive from last year that's looking sickly!

My crop is still indoors (too cold at night, in the 40's), with nice afternoons outdoors.

These plants (3 in one 2 gallon pot.. ok, bucket with holes drilled in the bottom) wintered indoors, and looked healthy until two days ago.
They got the reccommended dosage of a 3-2-3 organic fertilizer, with water.
They got some epsom salts with a watering last week.
The rest of my younger peppers of the same variety and different varieties, are not showing these symptoms - only this pot.

Oh, and fyi, I know three plants in one bucket is overcrowded... I'm planning on declaring a winner and culling at least one, maybe two, of them... (but, but, but, I kept them alive all winter!).

Did I overwater? Overfertilize? Over-worry? Most importantly - can I fix this!

(Will try to attach pics, if they're not showing up, give me a few minutes and I'd edit and add them...)

Having a bit of trouble adding images as images from Google Photos on a Chromebook... But here are links to the images while I tinker!
 
https://drive.google.com/open?id=1EHsDqCXl3kU9v_85y2OiobcIB_afaK_myg
 
https://drive.google.com/open?id=1OKr7kvAvtYsLNIU829zqohwTk8UO27SQ_Q

Hmm... apparently I'm not allowed to edit... (probably too new 'round these parts... I understand!).
 

 

 

Looks like sunburn/light damage to me. Have you been moving them outside at all during the warmer days? The indoor plants need to be hardened off before going outside in the harsh sun. If not, did you recently get some new lights or move them closer?

Well, you can't over fertilize with that organic fertilizer that you've mentioned,at that dosage. (or probably any dosage of it, provided that it's a dry fert) Roll the leaf over, and take another pic, if you would, please.

how long in the sun in the afternoon ?  Looks sunburnt ,  gotta ease them babies into it ,    

That is sunburn

Thanks all!
Tried to get a pic of the underside of the leaf, but it's now too dark and my phone is taking dark pictures (naturally!).  The undersides of the leaves look normal.
 
Sunburn?!?!  Wow... I think that plant got a whole two hours of afternoon sun.  And not that nice hot SOUTHERN California sun either... This is Far-Northern California sun... very similar to northern Scotland sunlight - when the clouds part.
 
It IS possible that the LED grow light I have over the plants may have been directly over this TALLEST one a couple days ago too.
 
I will be more mindful of the amount of light they get until they're acclimated.