Sorry bud i must agree with Clonex , those plants have had a hard knock life even for a first timer as I am one as well. I hope there is something that can be done so you dont have to scrap this grow I know that would be horrible. The most important thing is that you find out what you did wrong so you dont repeat it next time. Cuz the setup looks good tent , 400w mh/hps but i dnt see a exhaust fan or oscilating fan. Looks like there is no fresh air in and no old air being pulled out. You definitely have at least a month left till harvest if you can make it , I would flush a few times then start back 1/4 flowering nutes and see what happens cuz I dont think you can do any more harm.Good luck.
Happy Growing!