Hi
@Danno! This looks like pH fluctuations, and the beginning of a nutrients lockout. Get a pH pen asap and make sure your solution is always buffered within the 6.2~6.5 pH range. Now about the overwatering, be warned this often leads to nutrients-lockout issues. Roots need to be on a wet/dry cycle to properly develop and spread, searching for water. Do you let the soil dry a bit between each waterings? Let your medium dry and flush it with plain pH'd water at 6.2pH with the lowest EC. Then let it dry again, help it with a small fan blowing onto the container's surface, and once it's almost dry give it a good meal following the schedule of your choice with the fertilizer of your choice. I can recommend BioBizz, GreenLeafNutrients, GreenBuzzLiquids, these have worked great for me with FastBuds strains. Hope this will help, let us know how this goes, happy growing! 👊