dying? :(

my 3 week old plants are starting to have white spots on them and also the cotyledons are turning yellow and look like they are dying and some of the top new leaves on one of them look like its dying.
maybe im overwatering? or underwatering? help pleaaase :(

don't trip it looks fine right now. By the looks of the soil it may be a bit underwatered, but don't go overboard with it. Possibly your soil is too coarse for the plant but I don't think that would really hinder it in any way. What is your lighting and water schedule. How much? Do you have any fertilizers going cause you shouldn't.

well at 3 weeks i usaully start feeding nutrients.
they do look under nourished
and the yellowing could be a magnesium deficiency, curable with epsom salts which can be aquired at ya local chemist
mix about half a teaspoon of epsom to 1 litre of water, making sure that it is completly dissolved ,and water like normal with the solution
i also spray down the leafs when the lights go off and this seems to help
hope this helps m8
cheers all :)

well after a closer inspection they dont look that yellow on the top
and the 2 leafs that are going yellow on the bottom are perfectly ok, as
these 2 leafs hold all the nutrients for the seedling, once the seedling has used up all these nutrients the leafs will look crispy and fall off , then you can introduce nutrients to the plant this usally takes 3 weeks
cheers all :)