It looks to me like it has been sitting for too long in over moist soil leaving the plant with little air to breath in via its roots during the respiration cycle plants go through when lights are out. With no o2 being able to be uptaken by roots, the carbohydrates break down into alcohol rather than breaking down into co2, h2o and energy.
It is important that the media you use can retain moisture, but also allow roots to breath. It is also just as important that you water thoroughly and let root areas dry out before watering again, work with your plants, watch their cycles, how long it takes them to drink the pot media dry.
Over watering, and moisture sitting too long around root areas will stress the plants and can also lead to nutrient deficiencies even though you are feeding them, the roots just do not uptake the nutrients, in fact, the reverse can happen with the reverse osmosis that takes place in roots and nutrients can leach out of plants along with moisture....even when you are feeding them. The common factor is over watering and/or media that does not allow for air to exist in the root area.