Bark Peeling at the Base of a Weeping Cherry?

I have an 8 year old weeping cherry tree with peeling bark at the base of the tree. The trunk is also sunken in a bit under the peeling bark. The affected area faces south. Could it be from the sun? I also found an insect casing at the base of the tree, it looks like a pupa case. Could I have a double problem? I'm not sure what to do to save this tree. Otherwise, it seems very healthy. Hope you can help!