OK, when I have a problem like this, I empty the pot of all its contents, give the neem oil treatment all over the plant and roots. Spread out the medium on the ground and spray neem oil/detergent on it too, would be nice if you have sun to dry this for a day or two. Then put them all back together and my plants start looking happy and grow beautifully. This has been my experience so far. You might want to try it. Good luck!