Sleep Paralysis

Hiya all,
i had a really, really weird experience last night and I can't get my head around it. I awoke early dawn (i knew this because I could here the birds outside, but it was still dark). It was the smell that awoke me, it was a waxy, musty smell, a bit like an old combat/barber jacket. When I opened my eyes there was 'something' lying on me, I say something because I don't know what it was. It was smaller than me (i am 5'2") and was wearing a barber/combat clothing, it had a hood over its face so I could not see it. I thought someone had broken into the house. I didn't know what was happening. I tried to move, to shove this thing off me but I couldn't move a muscle, I couldn't even blink, my eyes were wide open but I could move those! I felt like I was getting pushed into the bed, as if this thing weighed a ton. Although I could not move at all, I could 'feel' the shape of its body on top of mine, like its head on my neck and its hands pressing on my wrists. I tried and tried to move and couldn't. I tried to scream, to shout out and I couldn't. I eventually managed a whisper. I said my partners name to try and wake him to get this thing off me. The second time I manged to croak my partners name hands went around me throat. I kept thinking in my head no, get off me, and managed to croak my partners name four times. He still didn't wake, I could see him out the corner of my eye sleeping soundly, softly snoring. Our dog who normally sleeps in his basket in our room was outside the door frantically wining and scratching to be in the room. I was aware of all this happening. Kike I say I just kept thinking no get ff me and eventually it stopped and the thing was gone. This all happened in a space of minutes. It has really, really shook me up as I have never experienced anything like it in my life. It was terrifying. When this thing got off me and I could move I was hysterical. I opened the bedroom door for our dog who came in with teeth barred looking around the room, after he was satisfied there was nothing there he came and licked me to death bless him. Partner was awoke and just looked at me as if I was a weirdo until he seen the marks on me. So he is freaked out now.
Anyway, can anyone explain this? I had red pressure points around my neck and on different parts of my body afterwards, so unless I had done this to myself in my sleep before I had this experience, it can't be explained. I would really appreciate some idea's of what has happened here as it has really, really freaked me out. Oh, and by the way, I am in a normal state of mind!
Love and light
wendy