What should I do if everyone seems to be against me?

Sometimes it seems to me that the person I communicate with over the network is not the same person at all (even people I know well). This happens sometimes spontaneously, and sometimes because of some reason, and I start to think that this is another person writing to me from his account and trying to mock me.It also happens that sometimes it seems to me that all people are against me and they are in cahoots (do not communicate and do not pay attention). I wouldn't say I'm a bad person, though.