Hi,

Thanks for your question. 

Let's see if we can rule out canker. "A canker is really a symptom of an infection by various fungal and bacterial organisms. The pathogen often enters the host through an injury or open wound. Once the pathogen enters the wound, it can spread under the bark. Canker diseases frequently kill branches or structurally weaken them, making the infected branch more prone to storm damage." (from the Morton Arboretum)

Do you see any bleeding (here are reference images)?

The pictures are great. Very helpful.

That said, I’m going to suggest a couple of possibilities and recommend that you consult an arborist for a reliable diagnosis. We typically suggest working with a tree professional for disease management because of the financial value of trees and their significance in our landscape.

The white worm you were able to photograph may be a bronze birch borer. You can read more about them here. Note that the window for treating this pest is now (early June), while the insect is in larva stage.  

If there’s a fungus present it would be what’s called a crust fungus (referring to its form). Fungi often, but not always, exist on decaying tree material. Again, an arborist should be able to tell you if the fungus is of concern.

The pictures don’t show the entire crown, but I didn’t notice any foliar damage or dead/dying branches in the upper part of the tree (often another sign of the borer).

If you can find another worm, compare how it looks with the description on the Penn State page linked above. I think that could be a good clue.