I just bought a Meyer Lemon Tree, that was very healthy, beautifully healthy. Lush, dozens of blooms that smell wonderful. And 2 huge lemons hanging on it. I set it in front of a sunny window. It gets great light all day. I water it when it feels dry once a week, or twice if it feels dry 3 inchs down. I have not fertilized it yet. I have only had it a month. It started this after about 3 weeks. Many leaves each day on the floor. I am very concerned. I don't want to kill it. Help, what am I doing wrong, or not doing? I feel like a lemon tree killer!