I think your overwatering and need more air flow..I had this problem early on and solved it by letting the plant go until it shows visible signs of wilting..then only giving enough water that the soil becomes almost dry within 48 hours. You may have noticed that some growers measure the amount of water they give their plants. Also, a fan is definitely helpful. I also noticed that during flowering sometimes humidity alone is enough to keep them going, it also brings out the color at the end of flowering. A good indicator of over watering is the leaves are puffy and the tips curl downwards. I try to keep my leaves sharp and pointed slightly upwards. You may encounter a problem if you have fertilized in that when the soil ddries the nutrients become more concentrated and fry the leaves. If you use a really good organic soil mix you don't even need fertilizer for an auto flower. The life cycle is so short the soil provides plenty of nutrients. a plant can only handle so much before fertilizing becomes a negative growth factor