Root problem?

This plant/seedling is 16 days old. About 4 or 5 days ago it started showing signs of over watering, leaves were drooping. So I proceeded to let the soil dry out, and although the soil seemed dry, it didn't get much better. The bigger leaves towards the bottom started turning brown about 3 days ago.

I did more research, and I figured it was the 1 gallon pot I had it in previously. So, I transplanted it into this little "pot" which I made from a Gatorade bottle and athletic tape. I poked a shit load of slits and holes in the bottom for drainage. It does now seems to be getting slightly better, and I watered again yesterday. I'm just hoping it's not a root problem, and just an -overwatering / too large of a container for the plant size- issue.... what do you think? I'm using Marshydro LED 18/6, Temps are good 65-78f. This is my third grow (grow 4 plants at a time usually) and have yet to experience this.

I have some Hash Plant seeds germinating, can't wait to get those started

Thanks!

Mike

This looks very similar to some dieing leafs I had recently after having 4 plants go root bound and Fucked them up a bit on transplant from a 3 gallon to 5 gallon pot. Hard to say though it's only 16 days old. What are you running the PH at? Looks like a cal/mg issue possibly. transplanting down sizes sounds pretty stressful to the plant this early too.

looks like over watering and over feeding. what kind of soil is that and what, if anything have you fed it?

blow one of those pics up. see all the stuff in the soil like crystals and bubbles? time release nutes, and possibly something to retain water. and no perlite....need better drainage, either perlite or coarse sand, or both