Seek therapy or counseling.
It is not at all uncommon to experience feelings of depression. Many people experience highs and lows that can be difficult to cope with. Drug users often are people who are attempting to self-medicate for their psychological issues.
The problem is that drugs do not treat mental issues themselves. They simply treat the symptoms. Working through problems with a mental health professional is a much more effective and long-lasting way of treating a psychological or emotional problem.