I heard motion coming from down my hallway, then a swift sound of wind

My door knob, I kid you not, started to slowly move, not back and fourth, but in and out like this door was being opened

Whatever was on the other side could not turn the knob first

I halted, all thoughts, all actions, and my eyes grew wider

I stared deep into the door for a moment and shivers when up my spine

Why? Because my roommates are newlyweds and they left the house about an hour before, they went to drink and I knew they were not back

I had little light on in the apartment; I didn't have any fans going I had no noise. Then I heard some kind of god-awful breathing on the door

It was close, really close to the door, I am not exaggerating this story, it was breathing like it had holes in its lungs, and as though it had no lips, the sound came out like it was breathing and smelling the air at the same time

Surely whatever this was could have entered regardless of a simple wooden door, but it did not

It was huffing and wheezing outside the door

I recall the feeling of this creature moving from a tall standing point to a low lying down at the bottom of the door where it meets the floor. My heart was racing, my head was pulsating with my heart, and I had a huge adrenaline rush, I could hear my heartbeat, and every other noise around me

I froze, this odd event lasted about ten seconds, not long but enough that I slowly stood up and put my hands in my pockets and waited by the door for several minutes before opening it

When I did finally leave I was nearly in tears with the thought that I was being hunted, and my hands for the first time that I recall were trembling; I could not stop them they were so shaky, it was beyond me. This apartment I live in has nothing of value or any background stories, this thing has followed me home

I am a hiker, climber, nature photographer, and a caver- I respect what could be a higher being of light, but I am not however religious

I can not explain why this event took place, but I do believe it is still here with me, and it wanted to harm me. I am in pursuit of this creature now, what do you believe this all means, and what is it?