BIG problems!

i've been having allot of trouble wit dis grow! it was all going fine for the first month den i got rust (fungus) that covered my plants with brown rusty spots after i cured this i had some nute probs and now i am having ph probs or something anyway here are some pics so try to see if you know what my prob is. peace

pic 1, is the plant b4 it had ny probs and the rest are what it looks like now! you can see the obvious difference it looks like a diff plant now! the last pic is from a diff plant that is having some probs too.

i forgot to add the im using a 400watt hps light.
i have been flowering for 3 and a half weeks.
i am using bio buzz nutes.
i water wheneva they get dry.

i really need help as you can see!