I keep seeing a black shadow & I need to know what it means
I'm 16 years old and about a year and a half ago, in October, I started to see a black shadow. The shadow is the figure of a tall man wearing a top hat. The first time I saw it, I was in the car taking my friend home. The shadow walked in front of the car as he tipped his hat. I freaked out because it had startled me, but nobody else in the car had seen it.
A month or two later (late November/early December), I was in class and just happened to be looking out of the window. I saw the figure again as he was walking by and my heart started racing. The shadow was tipping his hat again. I looked away, and looked back and the shadow was gone.
A few months after that incident (around February), I was walking out of my mom's room and I saw the shadow man walking down my stairs. He was literally two feet in front of me, but he kept walking down the stairs. Again, he had been tipping his top hat. I called for my mom and told her what I saw, but explained that I thought I might just be seeing things. Our dogs were outside and neither my brother nor my dad was home. We also checked all of the doors in our house and they were locked.
In April of that year, my grandmother passed away. I talked to my Native American friend about what I had seen and she told me that the shadow could have been quite literally the "shadow of death", warning me that my grandmother was going to pass away.
I didn't see the shadow for nearly a year. Last month, I had a strong feeling that I was about to see it again. I drew a picture of the shadow and showed it to my mom. We talked about it and I realized that I'm not scared of the shadow, however, after I see it my heart starts racing and I seem to become more alert.
I saw the shadow again two weeks ago. Now I really am starting to get scared, even though the shadow has never hurt me and it always tips its hat at me, which is supposed to be a sign of respect.
Does anybody know what might be causing me to see this shadow and how I should handle it?