Hello. I planted a lemon tree 3 years ago. Actually, it sprouted from a seed. Everything was fine until this year. I started trimming it because the branches were growing thin and tall, and I wanted the tree to be smaller and denser. I don't know what happened, but the young leaves fall off as soon as they appear, leaving only the stem. The roots look okay. I thought maybe the pot was too big, so I replanted it into a smaller one. No change. I've been using organic fertilizer with no change. New leaves appear, but they fall off shortly after and are twisted with yellow veins. The tree has stopped growing. I'm afraid it might die completely. I don't know what to do anymore. Please help.