All of a sudden so many apps stop working All of a sudden a lot of apps don't work any more, and some randomly give messages "unfortunately ________ has stopped working". Is there any way to go about trouble shooting this?

Shazam and Strava do this a lot. Facebook is unstable and closes unexpectedly. I restored from a working backup, but it was actually after this that things started to go wrong. 

Firefox would never connect to the internet.

This is Android 4.4
Your image is probably unstable, and at this point it's probably best you use Titanium Backup to backup your apps that are working and leave behind the ones that aren't. Then just flash an entirely new image and restore your backup from Tibu. As far as what caused it, nobody can really tell because you haven't provided much information. If it was working previously, you have to think about what you changed. That's usually the culprit; What you've actually changed.