What type of medium: soil What brand and type of soil? IDK Indoors or outdoors? Outdoors in nice weather indoors in bad weather What strain? bagseed How old are the plants? 3 weeks into flowering What type of lights and how many watts? Sun/23watt cfl How far from the lights? 3 inches What is your watering frequency and source of water? 3 times a week/ sometimes it gets rained on What, how much and when was it fed? NPK? Miricle Grow all purpose plant food / half liter mix/ every 5 days. What are the temps and humidity in the room? whatever it is outside usually 80 degrees What size pots? 4gallon Any bugs? Look real close. no Any other pertinent info? I left it out during a 2 day rainstorm one night but i don't think that would do much Idk whats going on could it be fungus? if so how do i kill it. Is this supposed to happen? Because the buds seem to be looking fine. Any help would be greatly appreciated. If you need more pics let me know.
Looks like a calcium def. If you check out the plant abuse thread at top of this page, there is a link thats shows many ailments. Hope this helps.
I've recently had some similar issues with a few of my plants, I've learned a main thing is to check pH first and foremost before supplementing anything, because it could be a lockout problem. If your pH is within range, I would recommend something like Cal-Mag, which has seemed to help my problem considerably. I might be a little off, but almost looks like what could be a K def. also.