I am into my 7th week of flowering having done 36 days on 12/12. All was fine up until about this time last week. I have the most severe deficiency with one of my strains but on multiple plants. Critical kush, grown in soil, vegged for 8 weeks. The most Wierd thing started happening to the leaves. Firstly small vibrant orange spots appeared towards the centre of the top sets of leaves, this has since engulfed the leaves within the vicinity and turned into a dark rusty brown. From this point I feared magnesium deficiency due to the tap water supply around here. But with me being so far into flowerin now in really worried its more serious. The leaves (once 80-90%) brown and crispy dry curl up at the tips. And then they almost just fall off the plant. They are starting to affect the buds tiny leaves at the very top causing maturation to slow down.. I'm really really worried as some have really slowed down growing and I really need some help..... Any suggestions based in what I have said? I've looked time and time and time again at common "defficiency lists and ways to try and diagnose them" and I keep coming back to either manganese, phosphorus or potassium..... Any help?!?!?!?!?