@boagie,
First, I would consider the normality of the experiences you have. I don't know how normal or abnormal they are as I am not having the experiences, but humans do normally go through periods of relative bliss and relative depression.
Mostly, though, just examine the problem. Check up for yourself and ask why you feel empty, what could fill the apparent void, what should fill the apparent void.
Nothing really beats sitting down and focusing on the problem. The trick is to be productive. If we spend our time dwelling - oh, this is so terrible, so terrible, so terrible - we just makes ourselves sick. Look deeply.