Hi, yellowing leaves is a typical nitrogen deficiency, leaves at the bottom right is potassium. You gave it some grow nutrients, it should improve with in a week, I would also recommend to give it a cal/mag and some micro, don't over do it though. If you won't see an improvement with in a week, than flush would be an option, otherwise I wouldn't flush the organic soil unless you absolutely have to.
Buy the TDS meter, and take some reading after each watering, it will give you a good idea about what's going on in the root zone.
Good luck mate