some of my !!GIRLS!! are sick

thinking 2 of my girls are sick, temperature at 78-80f {26-27c} lights on, 68-70f {20-21c} lights off with a 45-50% humidity. Last time they was watered was 3 days ago, last feeding was on the 4th Formula 2: Bud/Bloom 2-4 weeks depending on light and water consumption the soil is still moist not wet. this is the 3rd day but they usually perk up but yesterday and today they are not perking up. I am now seeing purple leaf stems and some color discoloration around leaves is this a sign of cooler temps when lights off should I be worried and concern about them being sick what should I do to make them feel better.