Self Injury while Asleep?

Hello everybody, I've been having these symptoms for about 7 years now, I don't know exactly what it is, so I don't know what to do about it.

Every couple of nights I have really intense, terrifying nightmares. I thrash around and jump out of bed sometimes. But when I wake up, I find out that I've actually received the wounds on my body that I got in my nightmare. Sometimes I have huge slashes across my back or chest, puncture holes, bruises, burnt skin, black eyes and things of that nature.

I've gone to dozens of pshychological doctors, and specialists, to try and figure out what the heck is wrong with me. But when I tell them what happened, and show them the injuries, they say that I am just making it up, and hurting myself while I'm awake, just to get attention. So they don't do anything for me. I've had a couple of sleep studies done also. But those nights, I happen to not have any of these nightmares, they don't happen every single night. The results come back normal.

I've putten all blunt and sharp objects out of my room when I go to sleep, but it still happens. I've put thick, soft gloves on my hands when I go to sleep, but that doesn't help. If I had the equiment I would film myself sleeping like they did in Paranormal Activity hahaha.

But seriously I am at lose as to what to do, and I am very scared. Has there ever been any cases of being hurting themselves when they're sleepwalking??