How come i have stomach pain while i am having a nightmare?

Multiple possible: Some nightmares may include visceral sensations. Also, stomach pain could precede a nightmare. How long after eating, did you lie down to go to sleep? This could be yet another factor. You list no medications or medical conditions in your accompaying information, so i suggest please working with your own physician who knows you, on this. Take care.

Nightmares and stoma: If your brain is in fight or flight mode during a dream, neuropeptides are being produced in higher volume in the limbic system(brain) and in the digestive tract. this is what produces the sensation in the stomach but we interpret the sensation by how we interpret the event. Please see my No More Nightmares book and Planned Dream Intervention to learn how to not be bothered or woken up by dreams.