In late spring I have bought a potted tangerine tree. After a few days, some of the leaves stated curling and falling off, but some leaves fell off without being curled. As soon as it warmed up, I started bringing the tree outside during the day and left it outside all day in mid summer. It did great and new leaves came out and even some flowers. At the beginning of the fall I brought it back inside and the curling and falling leaves issue started again. I am not sure if it is over watering , under watering , temperature or any other issue. The tree is in a room facing East near the windows and I have closed the vent in that area. I have fertilized it with Miracle Gro once in the summer. Can anyone help me with some advise on this issue please?