Leaves wilting in fourth week of flower. Please helppp

Okay. So I have 3 girls all in week 4 of flower. This is my first time here so I’m gonna ask a couple of questions. Please helppp!!!
Lady 1- suddenly one stem was dead this morning. when I checked it it was already kinda broken but no one had touched these girls. And the rest of the plant looks healthy af. Can it be root rot that’s gonna slowly kill the whole plant ??
Lady 2- the bud is filling out between the pistils. Today I noticed 3 fan leaves on the lower side that have wilted and are ready to fall. Not much discolouration tho. Is this normal or it the root rot spreadinggg
Lady 3- going through nutrient burn. I’m scared it’ll reach the bud before I can flush it out cause I don’t wanna over water it. The pistols are kinda turning brown although the bud is still filling out.

some general info: the room is between 23-27° C and humidity is around 50-60%. I have a 300w led grow light

I’m very scared for the second lady guys cause this is my first grow and I’ve come so far. I don’t want things to go wrong now. Cause all of them look healthy from the outside but things are still happening. Please help!!!!

each photo is of the respective girls







The wilting leaves one is happening fast. Please. Any suggestions would help

What are you feeding them, and how much?

Looks like to much N?

Post more whole plant pics for help.
It looks like a nute issue and potentially heat/fans. The edges may have nute burn but there is more to it i think than just nutes.

I've seen tons of nitrogen toxicity this week. More than I've seen posted in the past.