What i am suffering from. Plz help me.

I am 22 year old preparing for government exams.since past 7-8 months i am suffering from severe mood changes, swings, anxiety, fear, loneliness. I was even cheated by my close friend few days back, since then i am in a state of severe guilt and pain. although i am a topper of my university, i am not able to focus on my studies at all. my mind stays sad in every situation.i dont even like to share my room with any girl in hostel.i dont like talking to anyone anymore.i have lost all belief in me.i feel lonely so much.but as soon as i reach i feel good with my family.i am living in lucknow since 4 years.lekin ab har waqt ajeeb sa lagta hai.pichhle kuch mahino se i have not slept at night.i feel like crying and purposeless all thr time..i. Am not able to share my problem with anyone.plz help me..