dark, curled downwards and brown fan leaves

Hey mate shame to see its happening during flowering. Hopefully she gets through it alright! - what were your temps the past days? Low temps could trigger a molybdenum deficiency (solved by keeping temps >21c, around 24-27c during lights on) - you mention you watered the day before, root problems and overwatering can show near to random symptoms making them hard to pin point. Do you check the soil is dry before watering (e.g. by lifting the pot and guestimate with the weight)? - Does you soil drain well enough/ is it airy enough? If you soil is all compact and has a hard time letting oxygen through then the roots have a hard time and watering becomes less tolerant to mistakes and you can easily get salt buildups causing lockouts. --> If you soil is compact and you think this is the problem check if there are guides to make it more airy (no idea if poking it with chopsticks would help... I grow hydro since many years now). Otherwise its most likely a lockout so if you can't figure out what is wrong usually the approach is to flush them to kindof 'reset' the soil, and when they need water again then give with nutrients. Don't take my advice as the truth, as I mentioned I don't grow in soil since a while. Good luck to you and I hope they pull through!