leaves are withering Help asap!

here's the scoop my plant is in the 5th week of vegetation the biggest leaves at the bottom of my plant are yellowing and dying! but there is alot of new growth around these leaves should i be concerned about this spreading up the plant? HELp please

if it's just the first set of true leaves, they seem to yellow really bad sometimes, they rarely ever actually fall off the plant and die though.
I don't know if it's perfectly normal, but was once told they act as a garbage filter for the rest of the plant and soak up all the bad stuff, which is why they wind up that way.

ok this is the scoop....

when a plant first sprouts it begins by creating its very first set of embriotic leaves. theses leave die and fall off naturally once you first set of sun leaves develop. once the first set of sun leaves has matured and begins creating its next few sets of sun leaves the lower set will yellow, die and fall off. this is completely normal in the plants sprouting stage. the reason behind this is because the upper portion and newer sets of leaves growing need nutrients to develop. so the plant takes nutrients stored in its first(very bottom) sets of sun leaves to feed the leaves above em. that is y you will notice the lower sun leaves turning yellow starting at the tips. of course there are always other reasons for the tips turning yellow. if you are in your 5th week of veg it may be the simple fact your plant is looking for more nitrogen. never feed plants nutrients or plant food the first 4 weeks of its veg cycle. anytime after begin feeding your plant with a nitrogen supplement. do not go by the feeding directions on the back of your plant food. only use 1/4 of what is recommended! increase dosage every 2 - 3 waterings! hope that helped!

thanks!! wish i could ost pics but not able right now

could be from overwatering, not enough food, too much food or incorrect pH causing inability to use the food.
are you feeding them?
are you checking the pH?
does the soil have good drainage?
id guess its likely to be lack of nutes or overwatering causing it.