I think it would help next time if you took the plants out of the light to photograph them. The HPS gives a really yellow tinge that makes it hard to tell what's going on ya know?
Hm not quite sure. It could just as easily be Nute-lock from toxic salts in the soil. I'd say flush with ph'ed water (3 times the size of the container). Then give it some phosphorous, as it needs more of that than Nitrogen in the flowering stage.