Yellow Leaves need help!

My Afghan Kush is 3 week old and the 2 bottom leaves have gone very yellow with strange marks, what is wrong and what should i do?

That soil looks very compact to me, you may also be root bound and a transplant may do her some good, also have you given any nutes at all? if you have given some it may have been too much so a flush may also be a benefit but mainly I think you're soil is to compact and the roots are having a tough time