My plant is dying from the top down. What to do? How? Why?

Hi everyone. My plant which is supposed to be starting the 4th week of flower is dying from the top down. I am doing one plant in a 3 gallon DWC. Using Fox Farm Nutes with their feeding schedule. Added my nutes. Didn't see my plant for 24 hours due to work and not wanting light to hit her. So I get up early to take a look before work. Bam. Dying from the top down. Started a flush with a ph of 5.8. Now, a little more than 24 hours after beginning of flush. Same thing going on she just looks worse. I added a CfL the same day as the nutes. Added 2 degrees to the cabinet. Was 5-6 inches away from the plant. Turned it off since.
I just don't know where I went wrong. What or if I can do anything to save her? Sad sight. Was so proud. All like, damn, I can really do this! Then my worst nightmare. So all suggestions and ideas, guidance, condolences are highly valued and welcomed. Thanks.

Post a pic

normally i would say just cut out any dead with sterile tools and continue that as long as you need to. your in quite a pickle.

Hey, I would love to be able to shoot off some info I know you are in need of fast answers.. but I need more info about what is happening.

are the upper leaves yellowing, while the veins are remaining green? thats an indication of Fe (iron) deficiency. feed with trace elements containing iron.

if the buds are getting blotches of buds that are falling off and seemingly dead and spreading than its most likely botrytis (bud rot). cut away all infected areas and 1-2" below the infected areas, while sterilizing after each cut.

if the buds are dying at the upper areas and crunchy, looking like an infection but only at the higher ends of the buds and not really spreading, then it may be burning from overheating or light intensity.

hope that helps some, each bit of info is a clue making it easier to give you a solid answer.

Ccoastal