N deffiency or disease?

My plant is beginning to flower and I have switched to bloom ferts but and have recently just finished a bottle of veg which I have been using up until now. The yellowing of the leaves happened while I was still using nitrogen rich ferts so I'm a bit baffled. It seems to only really be affecting the fan leaves but I can see yellowing beginning to show on the smaller stem leaves too. What could be the cause and what should I do?

Kinda looks like lef spot disease. I'm dealing with it right now, not fun and its aggressive. There's a thread floating around about it on here from Tristyhawk I believe.

How can I combat it? I only have 2 girls and both are affected.

Okay I took them out of the greenhouse and completely removed any affected leaves and hosed the plants down. I disinfected the greenhouse and removed any foliage. I know it won't stop the disease but I hope it slows it rapidly so I can get to harvest.