Died ?

looks like Magnesium Deficiency or pH Fluctuations that cause nutrient lockout. Hope this helps. https://www.growweedeasy.com/cannabis-symptoms-pictures https://www.leafly.ca/news/growing/nutrient-lockout-cannabis

Thanks instart the flush now

I wouldn't add anymore food this late on in your grow in ideal conditions some go from bean to harvest in 8 weeks if you think has a few more weeks in her you could just give her a good flush to remove any build ups then feed with an organic bloom base nutrient with a mid to low EC and allow medium to dry before making choice to just flush and harvest or keep her going a bit longer adding other nutrients , some light defoliation of dead matter to avoid pests and disease may help you choose how to play it and if additional nutrients required to base I'd go very very light with some fulvic acids or look into making a compost tea instead of boosters and base nutrients