Hello. The symptoms you have mentioned briefly, if present for most of the time (if not all) for more than last two weeks can be classified as Depressive episode. However, this may need more clarification. It is possible that this may have happened due to a number of reasons. Being happy is a wish we all have, but if you have been upset for long, it is essential to seek help immediately. I am sure you have tried on your own a lot, but if unable to, try professional help.