According to the data you reported, you might be experiencing mood swings due bipolar disorder. Bipolar disorder is a medical term that covers a category of mood disorders in which anxiety is present and sometimes depression is manifested.
There are many subtypes of bipolar disorder. You might want to visit a psychiatrist because it might take longer observation period and more often visits for the most effective treatment to be determined.

Should this person describe these symptoms to his/her primary care physician? Physicians can prescribe anti-depressants.

its a chemical imbalance. it can be triggered by outside influences such as environment, relationships, etc. but at the core it is just a chemical imbalance

Certain environmental factors can trigger depression. Then, depression compounds deeper depression. For example, when I graduated from college, was unemployed, and living by myself with very little money, I felt hopeless. This initiated my depression. I believe some people are more susceptible to depression.

You need to see a physician, then ask him/her for a referral for a psychiatrist. Tell both doctors how u feel and demand a solution. Get a second opinion if you are not satisfied. Never quit until you are satisfied. You need to ignore anyone that dissuades you from doing this. In fact, just do it and don't share it with anyone if you think you will not get support.

We do not have time in life to be unhealthy. Godspeed.

Hi. I'm not a doctor but I believe there's a reason that only you can answer why you are lately depressed. Do you have problems with the people around you? Do you practice healthy and comfortable lifestyle? Are you striving for something that you really want but you can't still have?

As for me, I am also depressed because I just lost my job (because the company I'd worked with was experiencing bankruptcy so they closed it). I still live with my parents and I'm always insecure and with low self-esteem because I still can't get a job. My parents pension are just enough to buy their necessities. The worse thing is, my mother was diagnosed with cancer the few days after I lost my job and we have no savings in the bank to pay for her expensive treatment. I'm so ashamed of myself that I was thinking on suicide. But I realized that my mother needs me more so I have to be strong. One way of coping up with my depression is that whenever I have a free time, I always express my problems to friends that I can rely on. When I am alone, I go to social networking sites and see all the happy things that's going on in my friends there..I also participate in a lot of forum sites because people in forums are idealistic.

My advice to you is avoid being alone and keep yourself busy. If you can't handle your emotions, share it with someone. Participate in organizations that you believe that can help you...Don't lose hope..There's always a light at the end of the tunnel...