My current rented house. Has been living peacefully for the past 2 years when one day 2 months ago i suddenly heard someone knocking on my room door. I thought it was my housemate but when i check the house thoroughly there was no one except me. I call my housemate (we live 2 people) and found out he actually at his kampung.

It happens (the door knocking) 2 weeks in a row.

I never believe in ghost but I'm curios what actually cause this.

Also why now, why not during we first time move in.