I have searched all over the web trying to figure out what is wrong with my poor tree and what I should do to save it and haven't found anything that really pertains to what's going on with my tree. This forum has so many knowledgeable people, so I'm hoping someone can help!

I purchased the tree at the end of August from a local nursery, it was wrapped in burlap and laid in the back of a truck for transport to my house. It was healthy and full when it first arrived. I was advised to delay re-potting from the nursery pot and not to fertilize until the tree was acclimated to its new environment. The first week it dropped a handful of leaves, and then for months slowly and steadily kept dropping more. The branches that are bare are very brittle and now there are only a handful of leaves left on one branch (as you can see from the photo)! I've read that it should not be over watered, so I wait until the soil is dry. It still has not been fertilized. There are also some brown spots on the leaves that appeared when my brother was house sitting for us over Christmas. These have improved slightly since, but are still there.

Is there anything that I can do? Help! Thank you all in advance!