HELP! need to figure out what ails my plant!!

week 4 of flowering. everything was going fine until this week. tips look like nute burn, leaves drooping like overwatered, and why would th ph of my soil drop from a shade under 7 down to 5.5 in a week? I went ahead and flushed her really good today, hoping to raise my soils ph back up. at forst I thought it was nute burn, now I’m thinking it’s lockout. either way i flushed it with regular water. any help is greatly appreciated.
Indoor 2x2x5 box with 450 w viperspectra Led light
Fabric pot
unknown strain
raised bed soil with 35% perlite mixed in
no drainage problems
tested ph and ppm of water EVERY time
used ff growbig and calmag through veg, didnt flush for flowering and switched to dynagro bloom, fed her once full strength( big mistake, should’ve went with 1/4 of the suggested chart) 2nd feed was 1/4 strength.
haven’t fed her since because the tips look worse every day
Here’s a few pics i took while i flushed outside today... thanks in advance

how close is your light to your plant? Or is it growing outside? To much heat or lack of nutrients or to much nutrients could do that

do 5ou have an ec meter? what is the f33d ec ?
the medium EC should run about 50% higher 4hen feed ec
feed EC 800
waste runoff is 1000 to 1200 ec.
if its double at 1600 then that is 100 % the issue. it will manifest as a variety of nutrients issues but is actually just high medium EC
necrosis and chlorosis tend 5o go along with it . brown dead tissue and yellow
6oub got the flush right but 5ou need 5o replace the old solution with fresh new balanced with all 12 minimum nutrient N P K Ca Mg S Fe Mn B Z Cu Mo
flushing with half strength solution is better than straight water. the salt content actually pulls out more minerals liem growing a salt crystal on a string
If you do not have a ec meter s good rule of thumb is 2 gallon 1/2 strength solution per gallon pot size. . after that continue feeding normally with full strength solution with a 15 % overflow to help keep medium EC down