Having HORRIBLE SLEEP PARALYSIS... anyone know how to avoid or why this happens?

I have been having sleep paralysis since i was in high school (i am 29 now). at first i thot it was from using drugs(when i was younger. i am now clean) and didnt happen too often. now it has been happening at least twice a week for the last 3 months straight. it happened 4times so far this week and i dont know what to do. its to the point where im terrified and have to lock myself inthe bathroom for over an hour w the lights on. sometimes it happens 3 times a night and im not sleeping at all (which makes it worse). for the 1st time i experienced a loud ringing in my ears like a telephone and its happening when im more awake now and even after i sit up. this week it kept happening even as i was talking to my boyfriend and asking him for help. i have never been so terrified in my life. i actually felt my body lifting up from my bed as a black shadow was trying to take me,i felt. i am the happiest i have ever been in my life and am not stressed out or anything like i used to be when i first experienced it, i know it gets worse when u r sleep deprived but it has been happening when im fully rested. when i try n go back to sleeep it keeps on happening thru the night (even when im not sleeping on my back). last week my dog was sleeping on my chest n when i woke up my arms hurt ( in the "dream" my dog was scratching n biting me. i have seen the man who died upstairs last year try n pul me out of my bed. ive heard paranormal researchers have been looking in to this and want to know if anyone thinks its paranormal or some kind of hereditary or medical situation?? pleaswe help. i donmt know what to do.