It's most likely a watering issue or lack of air getting to the roots. Only water when the pot feels light to pick up. You don't always need to water on set intervals it's just a guidline. Cannabis likes a dry spell or drought every now and then, try moving a fan so it's blowing around the base of the plant and the containers. Don't always have to water to run off unless you're trying to flush something out and don't feed on every watering do something like feed, feed, water. I have a suspicion you're over watering or inadequate air circulation or the light is too close or both🌱👍