Brian, a photo is almost mandatory for this one. Plus, just a minor adjustment, but cankers are typically sunken areas of dead bark and cambium. Raised white areas could be lenticels, but again, without that pic, I'm fishing in the dark.

I added a link to a pic at the bottom of the post, thanks

That is bizarre and I have no idea what it is. Do the egg like things rub off? Are they just that - some sort of eggs?

However, whatever the issue, Caryopteris is a sub shrub so you could just cut it down to the base and remove any problem growth. You don't give your location but I imagine it behaves like a perennial and is killed to the ground in Winter in much of the US.

I checked out the article on mite galls which says you can let it go and then cut it back. But the description does sound similar. This stuff has killed a number of the branches in just a week so I'm not certain if it's the same thing. Let me get another photo when I get home, maybe that'll provide a bit more certainty.

I'm in Iowa, it actually didn't experience much (if any) die back this winter but it is 4-5 years old at this point. Before it recently started dying off it was about the size of a fully mature Caryopteris (3.5 ft wide, ~2 ft high)

I would cut the plants back whatever the issue turns out to be. It doesn't die back here but it still benefits from being given a haircut to keep it renewed. Caring for Caryopteris