N def
You need to keep giving some N during flowering.
For indoor growing one of the best NPK ratios for veg is 3-1-2 and for flowering is 2-1-3 Notice the lower value for P in all these as the P is not leached out of your medium growing indoors like it is outdoors.
Get some of your grow nutes into her maybe a half dose and do this maybe every 2nd watering.
Help her green back up a little.
the ratio above i have learned from RIDDLEME this guy is really wise and always knows his shit.
Your plants will take a little time to bounce back you dont want to try too many things all at once.
Give her some grow nutes as mentioned above the chances are that those yellow leaves are gonna stay yellow and not recover but anything that is still green will remain green.
If you want any more advice about this search for RIDDLEME's post about the Over use of bloom nutes.
J