Sick 2 week old clones

First off I would like to say hi to everyone this is my first post!

Anyways i have 3 two week old clones that I got from a friend of mine. Freshly cut they looked great.

But after they took root and started to suck up the juice, They have gotten sick!
Anyone have any idea's ?

Could it be overwatering?

It's a Mg deficiency. I'll bring some epsom salt by monday.

Here is a pic of what Mg def looks like when it's bad right side is veg and left is flowering.