Leaf issues.

I have a plant the strain is jack herer. I have it by a bush that it began to out grow. So I tied it down to a deck its beside to prevent it from growing above the bush. Well 2 days later it started getting yellow leaves in the bottom. That seems to be spreading up the plant. Is it related to me possibly stressing it when I bent it over (carefully)? Or am I deficient in something? All I've done is gave it miracle grow during veg. It is in flower now. Thanks very much in advance for any help.

Looks like an average outdoor plant to me. It might be in a bit too much shade, it's a bit leggy.