Flush it again, VERY WELL, with plain tap water at 6.7 and NO EPSOM SALT! You've scorched them, between pre-ferted soil, regular ferts, and epsom salts, and the heat will definitely make the symptoms show worse.
Use the flushing/pH instruction stickied at the top of the problems section. You've gotta get that extra magnesium out of the soil pronto. There's another trhead going in the problems section (prettykitty) with the exact same issue.