a plant will not flower and veg at the same time, it's two completely different stages of a plants life. If your plant started flowering outdoors, by now it will begin to reveg if not mature already. It usually take 2-4 weeks for a plant to switch back into the veg stage, you should see the buds start to look haggard and die off. I would feed it an all around 5-5-5 for now, and increase the n a little once it's past 12" or so. You're only going to want to use 1/2 strength for the first feeding, and only feed every other watering.