Hi, I wanted to see if you might know the answer to this question. Any help or info would be greatly appreciated!!

I recently purchased 3 spiral shaped, Eugenia Monterey Bay Syzygium Paniculatum topiaries. I planted two in the front yard and they are very healthy.

I put the third in my back yard in the screened porch area. I re-potted it in a larger container. It has been slowly starting to grow, but just this past weekend, I started to see the very top of the tree slowly turn brown and lose it leaves. Now, it has spread to the top portion of the tree. The branches have black bumps on them, it looks kind of like chicken pox.

Do you know what this could possibly be?? Should I return this plant to the nursery and exchange it for another??

Thank you,
Kimberley