Is it normal that i have to think about murder and blood to have an orgasm?

Anytime I either masterbate or have sex I cant have an orgasm unless I have a horror movie (all the saw and hostel movies are good for this) playing or I have to stare at my wall covered in replica crime scene photos.....lately nothing has worked besides imagining killing someone in very slow ways....currently the only thing that even remotely works is imagining someone in a metal chair as i turn a heating device up slowly....in this fantasy i can almost smell the burning flesh and soon as i can smell it I immediately imagine taking a garrot and pulling so hard I decapitate the person.....but even this is begining to fade....this isnt a joke...