Feelings of impending doom
Feelings of impending doom can be described as sudden sensations of overwhelming fear and urgency based upon the unfounded belief that a negative event is about to occur in the immediate future.   These expected negative events typically include some kind of medical emergency, a person's death, or the world coming to an end. This effect can be the result of real evidence but is usually based on an unfounded delusion or negative hallucinations. The intensity of these feelings can range from subtle to overwhelming enough to trigger panic attacks and a strong sense of urgency.
Feelings of impending doom are often accompanied by other coinciding effects such as anxiety and unspeakable horrors. They are most commonly induced under the influence of heavy dosages of hallucinogenic compounds, such as psychedelics, dissociatives, and deliriants. However, they can also occur during medical issues, cardiac arrest, mental illness, or interpersonal problems. 
- Fear of impending doom (AnxietyCentre) | https://www.anxietycentre.com/anxiety-symptoms/fear-of-impending-doom.shtml
- Is a Sense of Impending Doom a Real Symptom? (VeryWellMind) | https://www.verywellmind.com/sense-of-impending-doom-symptom-4129656
- Why a "Sense of Impending Doom" Is an Actual Medical Symptom (i09) | https://io9.gizmodo.com/why-a-sense-of-impending-doom-is-an-actual-medical-sy-1594012673