Help me please

So it's my first time growing herb I have one plant and it's about 3ft tall and about 4 weeks into the flowering cycle. Recently something has changed. The leaves are dying and falling off. I have been just waiting to see if it would fix its self. That has not happened. Also the whole plant is turning a lighter color of green. Please help!

might be a nutrient deficiency, hard to say without pics and more info.

its streching, give it some nitrogen

Alright thank you for replying I'll put up some pictures as soon as I can.