Lately I've been having these reoccuring vivid nightmares that I cant wake up from until im killed. Most of the time I can tell im dreaming but I cant wake up. I try spinning, I try to scream or close my eyes and concentrate on something positive but no matter what I do I cant wake up frome these nightmares.

Every night they are the same.
Im stuck in an old empty building(like an apartment or a ware house. its hard to tell. the layout is odd) and there is something with me. I dont know what it is but it hunts me down everytime. The building looks real, the dreams are veary realistic, but thats not the worst part. I can feel pain like in the real world. If I get cut or stabbed or bit I can feel sharp pain in the dream. Often I try to kill myself in hopes that will wake me up but one time when I tried to stab mysilf it hurt like hell and I didnt wake up, one time when I tried to jump off a staircase I broke my leggs and I couldnt move because of the pain(Isn't the sensation of falling supposed to work? Like that movie Inception?). I cant wake my self up from these nightmares and the only time I can wake up is when this thing in the building kills me.
And when I wake up. Im sweating, my heart is pounding and whatever part of me I hurt in the dream feels sore.

Can anyone help me? I've been losing alot of sleep over this, and im afraid to go to sleep. Im worried that ill eventually die in my sleep or something crazy.