What gives you the impression that others are badmouthing you? In cases like this, I have come to realize that it mostly boils down to indifference. People have their own lives and social circles to pay attention to, and as such their interactions with you would be neutral, which can seem cold.
If the above is the case, you’re not ostracized, you just haven’t found anyone to connect with (yet). I suggest you attend events, and hopefully you’ll get to know someone better.