Help?

so ive been growin this girl in my closet for about 3 months now and im ready to flower it. i was about to turn the lights off, when i noticed some of the tips of the leaves are curling and are brown alittle at the tips. i also noticed some brown spots forming on some of the leaves as well? im quite baffled at this because it has been doing so well. it is about 3ft tall, and has alot of growth on top now. so if anyone knows what may be wrong please feel free to let me know, if you need some pics i can thow them up tomorrow. please help dudes

laidher

i also forgot to add that the top leaves and newer leaves are lighter green/ yellowish around the edges...nitrogen deficency?? just wondering but though id also bring that to your attention

thanks for any insight

i will wait for pics