When a person is singling you out

There is this person whose presence I felt a couple months ago. I didn’t notice it but I think he knew about the people talking to me. He began to get upset at me even though I didn’t say anything to him but the other people did. The same day, he made me feel ill and to this date I think he is singling me out but because he thinks he can hurt me. I’ve never had someone treat me like that before.