I have a similar problem that I with my plants and I believe it was from misting/foliar feeding too you mine went pretty bad but once i stopped it is slowly getting better my advice don't folliar feed for awhile here is what mine looked/look like.
sd6515 Reviewed by sd6515 on . Not Sure How do these look, i'm not sure if i have Heat stress, or from what i was told when they arrived on Aug 22nd they this plant is normally light/pale green... 400w MH on 24/7 feeding only water - i think they are too young for fert Misting twice a day Temp - 75 - 84 Hum - 42 - 54% fan blowing light all the time. Arrival Day and now Rating: 5