umm.... did you mean to post a picture with this? No picture is showing. Without a couple pictures, knowing where you are located and a little bit about what conditions the tree has been through, we can't help.
Both of your ideas could be correct Boda, in which case your tree should slowly recover and grow away.
However......could you just take a sharp knife and scrap a small area of the trunk to expose the Cambium layer. It should be green and clean looking. If there is any sign of brown staining then it could be a sign of canker being active in the tree.