My Syntax Highlighter Died, What Now?

On my wordpress install (hosted by 11) a few years back I installed "Syntax Highlighter for WordPress" (I'm currently at 3.0.83.3)

Everything was going great until yesterday when something got updated and now my syntax highlighting doesnt work. I can see when "view source" that the pre tag that is created by my [cpp] tag is immediately closed on the same line instead of waiting for the [/cpp] tag. It's a bit strange.

Anyways, I went to check if there were updates for the syntax highlighter, and there aren't and it hasnt been updated in 4 years!

I know I could easily switch to another syntax highlighter, but they all seem to use different markup than this one did, and I have a lot of posts I would need to update.

In case it's useful info, I'm using wordpress 4.2.3 and it is at http://blog.demofox.org

Any tips how I could proceed? Is there any easy way to migrate without having to update every single post that has code on it? Thanks so much for any help, this is quite an unfortunate thing :/