Okay, this one's rather long, hope it doesn't bore you

It didn't bore me, that's for sure.
Yeah, so one night - I guess it was three or four days ago - I was up rather long, sitting at the computer and doing my translations. Then, at about 2 am to 2:30 am I got really hungry so I went downstairs, got myself a sandwich and a soda, went back up and the moment I stood in front of the door I heard weird banging coming from my room. I figured it was a bird that got lost in my room, since that had occured two times already (the windows in that room are rather large and during this time of the year I always keep them opened). Of course, that didn't make any sense because it was a little early for any bird to wake up and fly around yet, but I didn't think that far at that moment.
Anyways, I opened the door, and the only light was the one of my computer screen which I, as I remembered, didn't turn off when going into the kitchen. It was hard to make out, but it seemed like there was a person standing in my room, about 2 metres away, banging his/her head against the wall. Of course, I thought my eyes were playing tricks on me, so I turned on the light and didn't see anybody, but the banging didn't stop, even in a room that was fully illuminated. I figured the banging came from somewhere else. I wasn't really scared at this point, just baffled and thought it was weird, so I turned off the lights again to figure out whether I really did see a sillhouette in the dark or not. So I did turn off the lights and saw that shadow again, but this time it was standing much closer (now it was only about half a metre away), continuing to bang its head against the wall. I was startled so bad I dropped the sandwich and the soda (I admit, I also emit a cry) while jumping out of the room and shutting the door. That day, nobody was at home except me, so I figured there's nobody to bring and ran downstairs, took my keys and ran outside, locking the door. I went to my car just thinking "Gotta get the fuck away from here" and just drove for a little while, with no real destination. I just wanted time to pass. You can't even imagine how goddamn scared I had been.
After about half an hour of pointless driving I figured this was no solution. Also, my rational self told me it was probably nothing of harm, whatever it was. It didn't even look at me - so I made my way back home again. I went inside, and, after the first few steps, just stood there quietly, listening if there was still any banging. But I didn't hear anything, so I went back into the room just to find, right in front of me, lying on the ground - a sandwich and a soda. I kept standing there for a few seconds and then turned on the light. Seemed like there was no sign of any person having been here, except me. I picked up my stuff and bit off a piece of the sandwich when I noticed two cute little blood stains on the wall, roughly where the shadow was standing before. That actually was enough to make me shit bricks, so I turned to the computer to just turn it off and go to bed as fast as possible. Then, on the computer screen, I saw a notepad-file opened just saying (roughly translated) "See you next week." Without correctly turning off the computer I just cut off its electricity supply and went into the living room. Fuck no, I wasn't going to sleep in that room, that's been for sure. I ate the sandwich and drank the soda and fell asleep after a while.
There are no bloodstains on the wall any more.