Lady,
It could be depression, and Amy is certainly right about the 3 Cs.
But, before running to the doc for meds, ask yourself these questions.
Are you taking care of yourself physically?
Are you eating right and exercising regularly? Try yoga.
How about emotionally?
Do you give yourself positive affirmations? Do you treat yourself the way you would a friend? Do you do nice things for yourself?
Mentally?
When's the last time you learned something new? It doesn't have to be rocket science. What have you wanted to learn? A language? Music? Crochet? Painting? Do something to stimulate your mind.
Finally, are you taking care of yourself spiritually? Have you connected, or reconnected with your Higher Power/G*D? You may, but, don't have to go to your church, mosque or synogogue. Take an adult class there. Or read some literature. Become involved in the sisterhood section. Giving of yourself brings joy. Meditate too.
It's not easy to do all these things, especially if we are not doing any of them!
But, when I do them, I feel 100% better!
So, try to start doing something. Build upon success. I promise you'll feel better.
And then you can decide if you need to see a doc or not.
Shalom!