I mean it doesn't really matter what nutrient it is because more will not fix it. You found your problem. Maybe run some drip clean,
sea green or enzymes with water and get good run off the next 2 times at least but wait for the media to dry well in between. The products I listed will help flushing out the nutrients. Get the runoff down the a light feed
I would say one of those products with a good amount of run off. Then a flush with water next time and follow with a light feed after flush. Your going to see more issues to come but now it's about correction so it will get worse before it gets better.
I'm a new soil grower so see what others say but that's my view.