Trying to fix what thought was nutrient deficiency

Grow in FF OF soil an ff nute trio in 5 gal pot 600 watt hps have critical skunk gsc an few assorted auto’s WR an sugar black rose all are about 3-4 ft. water an feed at 6.3-6.5 into 3rd week of flower first time grow. So everything was going good then I basically lollipop after two weeks in flower. Left top two to three sets of fans noticed they started canoeing yellowing an brown rust spots. First thought an after researching thought MG deficiency an maybe not enough moisture so pH runoff an was all around 5.8 i freaked out a few of them lower started flushing with 8.1 tap an two tsp Epsom salt per gal let sit out 24 hrs Took about 4-5 gal h2o to bring pH up to 6.2-6.4 run off. While flushing an more research discovered probably just feeding to much an ppm was probably biggest issue but no ppm meter yet. I know bad move but it’s on order. Started in beginning with feed water feed then changed to feed feed water for couple weeks. I flushed 2 days ago when seen issue my question is is this going to help get back on track or is Epsom gonna cause more harm since it was probably just build up. When water an feeding never gave much for runoff. Learned alot in this first 90 days. how will I tell if it’s actually healing if the remaining fans are messed up? Also have about 5 weeks or so till harvest should I wait an no more nutes or give some before starting final flush. They were sugaring up nicely until two days ago an seems growth slowed. Haven’t used any cal-mag through grow. Any advice or info would be great. Thanks in advance.