1. What's the difference between an "employment certificate" and a "certificate of employment"?
Articles, man.
2. It's the middle of the night. I can't fall asleep because someone [next door/outside/whatever] is drunk and making a lot of noise, which is really annoying. I just got up to wash the dishes, which I haven't been doing for the past two weeks.
That's how I'd restructure it to make it sound more natural, anyway. It was correct before, but it sounded a little strange.