21 years old male with following problems:-  Extreme fear, Worries, Insecurity, Social withdrawal, Aggressiveness, Increased sleep and appetite,  Day-dreaming, All negative thoughts, One-sided love which is highly intensive, Short temper nature, Easily gets distracted by any person, Unstable mind, Mood swings, Loss of night sleep and increased day sleep, Weight gain, Loss of interest, Suicidal thoughts, Misinterpretations, Delusions, Highly sensitive nature, No daily routine activities... What is diagnosis? Is it serious case, what can be done?

What's the reason behind such problems? Kindly give your opinions.