No Idea what to do to help...

Your poor plant is exhausted and with a completely frustrated metabolism from being tortured with continuous lighting. 18/6 is optimum, any more is plant abuse. Cannabis undertakes certain metabolic processes during the night and since these plants are on 24/0, they can not do these vital processes and this is why this plant is suffering, an incomplete life due to no sleep. Nothing on planet earth is designed to live for weeks/months without sleep. Sleep is essential for a normal and healthy balanced life. Could you imagine going weeks without sleep? There is a very good reason why sleep deprivation is used as a torture technique - it drives people nuts! No doubt your plant feels the same. The fact the others seem ok is down to the fact they are "tougher" and haven't started sulking yet, but they will. A lot of people try thrashing their plants mercilessly with 24 hour light, however they only ever try it once, usually because the plants either give up/collapse or if they make it through flowering, the buds are crap. Without a rest/sleep cycle every 24 hours a plant can not function normally. Think of the 6 hours sleep as 2 hours to recover from the day, 2 hours to rest and 2 hours to get ready for the day ahead, and this is basically what occurs during this nightly 6 hours of sleep. 18/6 was derived at through 80+ years of research and is not a random number, it is the optimum amount of light that a cannabis plant can use before growth tops out, meaning running your lights any longer than 18 hours is basically a waste of electricity. Go back to 18/6 and your plant will recover and thrive. All your other plants will also grow a lot better when they get their necessary dark time and they can return their metabolism to a normal and healthy state. Be kind to your plants and they will reward you with prime flowers. Thrash them like machines with endless light and they will break down with exhaustion and be trying to live with a completely abnormal metabolism, and such a plant can in no way grow decent flowers. Hope this helps,.............. Organoman.