Ghost waking me up every once in a while?

I live in a condo, and back in January, the man across the hall from me committed suicide. Ever since January, every once in a while I will have something wake me up around 3-4 am. I usually am having a strange dream when this happens, then I suddenly wake up to something. But, I am being pinned down and I can't move at all. I can't move anything. Kind of like I have tons of weight on me... then it just goes away. Two nights ago, I had a strange dream. I woke up to a scream in the dream, but when I woke up, I still heard it in my mind, I think.. I was laying on my side at the time.. And when I woke up, I felt like there was fuzziness around me, and also I couldn't move. even if I tried. like I was being held down. then it went away.. I have been sleeping with the lights on for the past few nights because im terrified. what's going on..? I also have a dog who sleeps on the opposite side of my bed at the bottom, and I don't believe he wakes up to it. it doesn't happen all the time, but its happened about 4-5 times since January. I also don't see anything when I wake up. or im too scared to look. Whats going on?