that looks like a boron deficiency buddy
check it out The Complete guide to Sick Plants,pH, and Pest troubles! - International Cannagraphic Magazine Forums
it's toward the bottom hope this helps
Felixthecat Reviewed by Felixthecat on . Red/Brown spots on leaves during flowering Noticed these a bit ago. Really hoping its not mites(haven't seen any) or anything and just a nute problem. They spots are only on some of the top fan leaves. I am a couple of weeks into the budding stage. The pic is blurry. Some of the leaves have a more severe problem of the spots. Rating: 5