I had the same problem when my soil was not areated enough, I used a potting mix that got like concrete after a few days and it was smothering my babies, I repotted using an organic mix with 20% perlite and it recovered in about 3 days.

__________________
(Genesis 1:29-31):Then God said, I give you every seed-bearing plant on the face of the whole earth and every tree that has fruit with seed in it. They will be yours for food. And to all the beasts of the earth and all the birds of the air and all the creatures that move on the ground-- everything that has the breath of life in it-- I give every green plant for food. And it was so.

It's over or under watering. Considering it's done it just after you watered rather suggests it's over-watering. The way you can tell is that the leaves look limp and lifeless if they're under-watered, if they're over-watered they're firm but curled under. Not to be confused with nutrient over-dose which is leaves curled right under like a rams horn.

The cause of the leaf wilting from over-watering is the lack of oxygen in the root zone. This can happen from a variety of reasons from an incorrect watering schedule, incorrect watering technique, too frequent watering and not allowing any run off out of the bottom of the pot. You need to learn the 'wet/dry' method of watering and stick to it.

In the meantime, you can try adding some aeration holes into the soil by very gently pricking it with a thin stick - meat skewer, barbeque skewer about half way down into the pot - be careful with the stick that you don't start damaging roots. This should help get some oxygen down into the root zone and help aerate the soil.

How old are these plants? Did you get some lighting for them. VV