Weak stems/branches

Hey all,

I have 2 plants about 3 weeks into flower and both were showing nitrogen toxicity, 1 worse than the other. I flushed both and the one that wasnt as bad has rebounded fine but the other still has some bad clawing and now the plant wont even stay up straight, keep falling down under it's own weight. My question is whether or not this could be continued nitrogen toxicity or something else? The buds are tiny, barely formed anything yet but I have to tie up almost every branches plus the main stock itself to keep from falling over.

Any help is appreciated!

Pictures dont show much as I've now tied everything up as much as I can.

How much and how often do you water?

I normally water every 3 days just until I see run off which is usually about 1 gal and they are in 5gal pots. Although I just had a bad storm last night that pretty much destroyed both plants