It began approximately a month ago, when my parents moved to France and I started living by myself. I live in a small town on Vila do Conde (Portugal) .
At first, it was just some noises on the lower part of the house, like something was moving wood planks (when I was younger, me and my mother used to listen similar sounds coming from our attic. It stopped when our house was demolished, and we began constructing a new one, which is my current house). Since now I have one cat and one dog, I thought that they might be doing those noises because they are very active at night playing with each other; however, things started to get weirder. On the morning, several doors were open and I had previously closed them before going to bed. Again, I thought it could be my cat, since he actually climb to the knobs and try to open them, but I don't think he has enough strength. I locked the doors with the respective keys and it resolved the problem.
The "strange phenomena", let's call it, "moved" to my room, on the upper part of the house. I was feeding my fish (I have an aquarium) and I left their food next to it. I turned around and I heard the recipient rolling around my bedroom's floor. My immediate thought was "how can a recipient move itself to the table's corners and then fall?" I knew that the recipient was too far away to fall from the table. On that same night, the aquarium stopped working. The filter, the light, everything.
Several days latter, I was searching for my stress ball and I couldn't find it. I searched all my drawers and nothing. Then, something got my attention. I saw the ball rolling itself from under the bed to one of my bedroom corners. Just on the exact moment I was searching for it! This really freaked me out.
After this, several other things started to happen. On the middle of the night, around 3/4 am, someone keeps knocking in my main front door and no one is there. One of my locked doors opens by itself, and it cannot be the cat, since he can't rotate a key, and those persistent wood plank noises.
PS: I'm sorry if my English isn't good enough.