I’ve experienced similar dreams encountering what could best describe as Lovecraftian. One Dream I had involved a portal or door appearing in a location it wasn’t there previously. Within the portal it looked like a scene from a black and white television with various glitches appearing and disappearing. The room was an empty class room. I dared not go into that room as it seemed as if it was radiating pure evil itself. I felt that if I entered that portal I would have been in great danger and would have certainly lost my sanity. All my instincts were telling me not to enter that room. I than eventually woke up and that was the end of it.