You are speaking about two different things. First of all there are everyday life experiences. You can speak to speak to a talk therapist about that. However, clinical depression is caused by a chemical imbalance in the brain. That's why its treated with anti-depressents. If your life and the issues you experienced could be talked through it would not be clinical depression. However, clinical depression can be worsened by traumatic life experiences. I can't tell the exact difference but a psychiarist could. Also you said you had manic depression. Of course now the term is bipolar. The treatment for that is different from depression in that mood stabilizers (Lithium, Depakoate, Lamictal, I found Lamictal to have the best side effect profile) are used and anti-depressents would worsen mania so its important to be detailed with a psychiatrist. Do you experience mania or moodswings overall beyond depression? That certainly can be easily treated with a mood stabilizer. The best start is to speak to a talk therapist and then go to a psychiatrist to see if medication is warranted as well which it may very well be. For more information google "Depression Central".
aside from seeing a doctor its important to keep a regiment with meds- drfiter0213