I hope this answer finds you in better health than when you wrote it.
Low mood, negative pattern of thinking, mood swings etc are suggestive of depression
amongst many problems.
There are many ways in which this can be helped (Medication and formal taking therapies for confiremd clincial depression ) and if it is not , then as well, talking about your problems itself can help to a large extent.
Do consult a mental health care professional.