Seedlings wilting and going yellow

[Sargeantneo]

This is my second grow and i am having major issues already. My seedlings are maybe 2 weeks old and they are going yellow and wilting.

It can't be under watering as the top 1 or 2 cm are damp/moist, and it cant be over watering because i learned about that in my 1st grow and know how to avoid it, i even let the soil dry out for 4/5 days. so i don't know what is causing the wilting.
The yellowing is so confusing, the cotyledons should be providing all of the nutrients at this stage, so maybe it is nutrient burn? i am using sterilised topsoil which i know is nutrient rich but wouldn't think it can cause major issues like this. the white stuff is perlite by the way, that shouldn't be causing the problems.

they're on a 20/4 light cycle, runoff pH was around 6.8, temp in cupboard is pretty warm, maybe 28/30 Celsius, but the strain is Big Bud, which apparently needs a warm climate, i even left the doors open for a few days and that didn't make a difference either.

Please help, both of my seedlings are dying and i just can't loose them, i'm still trying to cover my losses from my 1st grow.

 

[spartacus420]

It looks like its stretching a little bit.. What kind of lights are your using?

How much are you water at a time and how often?

 

[Sargeantneo]

I water it when the top 1 or 2cm are dry, its usually every 3/4 days i water it with maybe 100ml water, no nutes.

lights are like 3inches away from the leaves, they are 23W energy saving (125W equivalent) at 1380lumens Cool White 4200K

 

[mr.maryj]

stop the watering in a pot like that u water once a week if that

 

[silasraven]

stop the watering in a pot like that u water once a week if that

every other day , but when its a seedling like that, back off watering every day.

 

[Flaming Pie]

closer pictures and please rotate them before posting.

 

[Ringsixty]

over watered

 

[Sargeantneo]

i dont know if its over watering. the only reason i say that is because when they started to wilt i re-potted them into a larger pot and the soil was bone dry all the way through. a few days ago i tried flushing them, but that hasnt worked.

If it was overwatering/under watering that would explain the wilting. however that wouldnt explain the yellowing, and the yellowing occured before the wilting.

yellowing has got to mean something to do with nutes/soil rite?