I bought a plumeria a little over a month ago and it was doing fine for the first few weeks. Then all of the sudden the leaves turned brown and shriveled and fell off. The same happened with all of its buds. I felt the trunk of the plant and it was mushy and shriveled looking. I was sure it was root rot. But now all of the sudden my plumeria has started growing leaves again and the trunk feels hard! Can someone explain to me what happened?