420Fastbuds Gorilla cookies

BAD WEEK! need some help here guys.. Brown / rust spots started to appear on the tips and slowly started yellowing leaves. Im following the master advanced nutrients chart and watering 2 times a week. Last week feed was 20 litres R/O water 80ml bloom A 80ml bloom B 40ml of every additive on the chart 20ml cal meg 30ml phup PH adjusted 6.50 After i started noticing the brown spots / leaves curlin up and stunted growth i skipped a feed and flushed with plain R/O water used 30 litres for 4 auto plants. Yesterday i watered again but cut the nutes in half. 20 litres R/O water 40ml bloom A 40ml bloom B 20ml of every additive on the chart 20ml cal meg 20ml phup PH adjusted 6.50 I still don't know what the problem is, if it is a excess of something or a deficiency..Looks like a cal meg deficiency but ive beed using cal meg since the beginning. Maybe i have excess nutes in the soil and resulted in nutrients lockout of cal meg or something else? since i water twice weekly should i water with nutes always ? The master advanced nutrients chart still sometimes confuses me. Please any help will be appreciated