Laboured Breathing In The Night

I'm hoping in posting this I can get some help. I'm real scared even though nothing bad has really happened yet. You see, for the last 3 years I've been hearing a strange breathing noise. The only way I can describe it is almost like someone on a ventilator.

I don't remember exactly when it started. What I do remember is going to bed one night and being just in that state of being asleep yet slightly awake and being scared by sudden breathing. I tried my best to ignore it and eventually went back to sleep. This happened every night for 3 weeks. I was getting really fed up with it and decided to figure out what was causing it, being that my cousin was in the room next to me and the wall was paper thin I took it to be her. So I waited one night and when I heard the breathing again I went into her room. Sure enough that is where the sound seemed to be coming from. I left it at that and forgot about it.

For a while the sound seemed to stop. After about a month the sound came back, only problem was the night it came back my cousin was at her stepmother's. I then thought well maybe it's my nan as she had very labored breathing, so I went and checked on her and thought yep it's her. I had also ruled out my grandfather as I heard it when he was off fishing. It then stopped again for 2 weeks before returning on a night where my nan wasn't in bed yet because she was watching football. Needless to say at this point I was scared. It started happening every night again and no one in my house was making the noise. I remember my nan saying my great grandmother who had lived in the house was on a ventilator and she had died in the backroom so I thought maybe its her. I left it at that and thought nothing more of the noise though it really did scare me when I would hear it.

One night I was woken by the breathing and decided to go to the toilet. It was then I noticed the breathing was coming from just out side the window it was always just outside. 6 months ago I moved out of my Nan's and into my uncle's (I'm running a youtube channel and his house is in a quieter location) for the first few weeks things were peaceful. About 5 weeks after I moved in the breathing returned. I got up and closed my window to block it out and never opened the window again. Recently the breathing has come inside the window it's still closed but the breathing is there it's really starting to scare me to the point where I stay up until 3 am when I know the breathing is gone or hope it is. I don't know what it is or why it's here but I want it gone. I've been thinking over it and I think around the time it started I may have brought 3 porcelain dolls into the house although I can't be sure. I've been thinking of moving them out of the house 1 by 1 to see if its one of them but the breathing happens at random times I don't think I would be able to tell when its gone.

Has anyone else experienced this or able to help me with it.