My question is, how can I overcome this? And how to feel okay alone in the campus?

It sounds like you have social anxiety social phobia. I will explain and give you some coping skills as well.

So it is important to remember that if you believe someone dislikes you, it is not a reflection of your worth, but it can feel very difficult to manage. One thing to do is to challenge these thoughts.  Is it because you catastrophize  where you believe no one cares?  Are you "personalizing" and deciding that others are not responding to you because it is your fault, and not perhaps because they are otherwise occupied or made a mistake by not contacting you?

You may assume that others don't like you and harbor ill will against you. You believe this is true, but in essence you are mind-reading and projecting your own thoughts.  The last option to consider is that you may be practicing "all or nothing thinking": if they are not responding to you then they must dislike you.

If you believe that any of these distortions may be true, you can reframe your thinking.  You can "reframe the situation." Give the people you feel don't like you the benefit of the doubt and try again to connect.  "Look for evidence" by challenging yourself to come up with evidence supporting your conclusion that no one likes you or wants you around.  

Try to distract yourself from these thoughts that are negative. So if you feel ignored by one group of friends, try to have a conversation with someone else. If you wonder why you haven't head from anyone, text or call one of them. Invite them to do something together.  Ask them if something is wrong.

If you still believe that "no one likes you," do not allow yourself to dwell on this thought. It is painful and unproductive. It is an easy feeling to indulge in and let overwhelm you.  It is also a way to "self-attack" which is very destructive.  It is feeding a more "critical inner voice" that says you are not good enough or deserving.  If this is true for you ask yourself: where did this critical inner voice originate from.  Often it is from experiencing hurtful negative attitudes that you were exposed to, especially by significant caretakers in childhood.  This experience can also lend itself to isolation and loneliness which you want to avoid. Loneliness can also lead to misremembering facts and only recalling or blowing out of proportion what was actually said or done.

If none of this makes any sense to you, then consider the notion of anxiety and social phobia. If people sense you are uncomfortable they will also feel that way - making being together uncomfortable.  Social phobia is the feeling of significant anxiety, self-consciousness and embarrassment because you feel you are being judged and disliked.  It can also be related to feelings of extreme shyness or fear that you will embarrass yourself shamefully.

Social anxiety/social phobia  can result from  heredity as well as learned behavior.  Talk Therapy and refuting negative thoughts can help. Seeking opportunities that feel safer and less threatening  with a smaller group of people where you can begin to feel comfortable and have corrective social experiences will help. Consider also joining a therapy or social support group to get peer feedback and exposure.  If in College, try to join a study group so you can interact with others, but with a purpose.

The physical symptoms you describe sound like a mild panic attack in reaction to the social situation and your fears.  Relaxation techniques and using positive self-talk to calm yourself are also helpful strategies.

I hope this is helpful and gives you some direction.