I can really relate to this. It's really hard when your mood plummets. Can you identify a trigger or isn't there one? There might not be. Either way you need to try and focus on what you can do to get through this tough spot. The first thing that helps me is to remind myself that I have felt like this before and it has passed. Seems simple but sometimes the dark moments can feel never ending. The second thing is to think about how to manage until it does. How can you take special care of yourself whilst up you feel fragile? Do you like bubble baths? Do you have a DVD or TV show you particularly enjoy? Do you like computer games? Can you call a friend or family member for some support or maybe just a laugh or chat? Do you do better with company oar alone? Do you feel so overwhelmed you just want to take a break and go to bed? Think about what helps you. These are just some suggestions but I really don't want to overwhelm.
Courage doesn't always roar. Sometimes courage is the quiet voice at the end of the day saying "I will try again tomorrow"