Hi, you have not mentioned the duration of your problems and many other necessary informatios.  But emotional outbursts without any reason or on trivial matter, feeling insecure and lonely, negativity towards self and others are symptoms of some underlying emotional/affective problem most commonly depression, it may be due to some adjustment problem or impulse control problems. They may also be the effects of substances or may be a prodromal symptoms of major psychosis. But they all have definite diagnostic criteria. It's not possible to say properly what actually is happening inside you.