Plant maybe drying out Maybe some advice??

I have a plant 4 by 4 feet. 1 week ago I n oticed dark brown spots hidden on the fan leaves mostly in the middle. Then the brown spots turned to yellowish brown spreading and drying curling the leaves and making them crispy. This is happening all over the plant. except the tops . Its 2.5 weeks into flowering. The top 3 sets of leaves on every top seem to be perfect. The odd spot but this drying happened fast if thats what it is and has spread to probly a quarter of the plant but yet it still seems to be producing buds stupid fast and growing tall stupid fast.

This possible, it grow to fast for thc production to get everywhere in the plant where it starts to dry out. Becasue it lost its smell around the same time? And its growing really fast, 2-3 inches a day.

This is the same problem I'm having. signs point to nitrogen dificiency. Try adding nitrate of soda. atleast thats what I did today and I have yet to see results... I'll post if I see any changes.