help! i think i'm going craaaaaazy!

I live in a residential building. I live on the seventh floor and my grandma, on the eleventh floor (of the same building). My granda's neighbor... idk, he's kinda weird. Every time i'm going to take my 狗 for a walk, he's staring at me (he's a little ond and he's got a wife). Once, i met him in the elevator and he started to ask personal things (my name, age, etc). And one 日 i went to a near little store to buy bubblegum and guess who was there! But today, he did the most weirdest thing: i was looking through my bedroom's window and he was entering in the building like a freak. With the both hands in the air, shaking, and looking at the both sides to see who was around. I need some help! Am i going crazy 或者 am i right?