It's a fungus. I had this same exact problem in new york for years. In the later stages growth becomes twisted and gangly and the purple areas are everywhere. The buds don't get as big, but they don't rot. They are more prone to mold while drying, though. This year I had one bud that had the problem, but in the past I've had entire crops affected. Since I changed grow spots I've barely had any. When I used tohave a big problem with it fungicides helped. It doesn't go away, but new shoots are healthy. If you got it in flowering what's done is done really. Smoking it still does the trick, but I wouldn't smoke it. I wondered if it also might be a mutation. The seeds that came from it grew out with the same wrinkly, twisted leaves and purple patches.