The only mod which isn't much is root and exposed stick everything else
Root by its self won't cause any problems.
If xposed is the only mod you have installed, which is actually a heavy and complicated system modification and you have systemUI crashes and now a camera issue... Then I'm sure it's something with xposed that's causing the problems. I would completely disable and uninstall all xposed modules and the xposed framework all together.
Also try running your device in "Safe Mode" for a day or more to make sure that it's not a 3rd party app. Safe mode can be run on any nexus 5, stock ROM or not.
Something to consider also is that not all apps and xposed mods haven't been updated to be completely compatible with 4.4.3+ and can cause issues and bugs on your device.
So... Your still on the stock recovery then?
I mean if the above doesn't work, then the only other options really are to wipe the dalvik cache (custom recovery) and wipe cache partition (stock or custom recovery) or to perform a factory reset through recovery... This works on both a stock or custom recovery.
Other than that you might want to just reflash your stock ROM, as in the stock 4.4.3 or 4.4.4 images or OTA.