Yes, as you have rightly assessed, you do seem to have a problem. But it could be very simple such as depression, hypothyroidism,
vitamin D deficiency etc. You need to take treatment under the guidance of a qualified psychiatrist. You will start feeling better within a few days to a few weeks. The treatment may last for a few months.You will recover and lead a happy life as before. Meanwhile you should avoid night shifts (if that's what you are doing). Also learn the art of pranayama, meditation and yoga, and spend more time in bright day light.