It certainly doesn't take a reason or a trigger for me to go into one. It just happens. The switch just clicks for no apparent reason. It is proven that the earlier you can catch it the easier it is to treat it. My psychs have always told me to call as soon as I start to notice the symptoms and the depression coming on. That way maybe they can prevent it getting worse. Of course I always wait until I am at the bottom. They up my meds but for me it usually just has to run its course. I would reach out to your p doc right away.