First Grow-Whats wrong with my plant?

My plant is nearing its 6th week of flowering and recently some of the leaves on the plant have been turning yellow. Any ideas on what might be wrong with it?
Anything helps,
Thanks.

It's normal for older fan leaves to yellow.
Although I can't see many yellow leaves in your pics, save 1.
The cause of said yellowing is simply cannibalism.
Your girl is sapping Nitrogen right out of the leaf because it can't find it in the medium(soil/hydro).
I would not recommend trying to supplement Nitrogen at this point in Indica dominant plants.
But, yours looks to be Sativa dominant so you might consider upping your Nitrogen if you are going 10-12 weeks.

I only put one pic on with the yellow leaves because its only in a few spots,
but some of the leaves yellow until the point where they wilt and fall off.
Are you sure that is still normal?

Yep, Just wait until they are about to fall off and dispose of them.
A slight touch is all that is needed to take off a dead leaf.
Wait till that point or you will cause further damage.
This is because the leaf still has a little "juice" left in it.
And if you remove it, the plant will just start taking it from the next leaf!!

Some growers keep trying to fight the yellowing all the way through.
They end up with extremely harsh buds that likely fizzle and pop.(You've been warned)
You still have some time to go, so I think it would be best for your to up the Nitrogen as I stated before.

Fact is, your plant is nearing the end of it's life and it's putting everything into those flowers in hopes of receiving pollen for the next generation.
Even if that means sucking her own leaves dry!!

I'm sure somebody else can concur.......