Reality or Hallucinations?

I am in the office room studying alone... My mam appears out of nowhere at the window scaring me in the process. I laugh as she enters the room smiling at me, my heart still pounding from the scare. "You scared me." I say. "I was just checking up on you" She answers. She does this a couple of times and then she stops as she goes to do her own thing. After a while I saw something or someone at the window I thought it was Mam but it disappeared as I looked away remembering my Mam was upstairs. -Scared- Now i always think or feel like someone or something.... is watching me. And from then on i always look at the window for reassurance that nothing is there or is something there but... it doesnt show itself?....