I Have Spells Of Waking From A Deep Sleep With

I have spells of waking from a deep sleep with the urge to have a bowel movement. While sitting on toilet I will have syncope then nausea cramping and diarrhea for 20 minutes. Sometimes I will faint before the nausea and diarrhea even begin. It's always during the night and only while sitting on the toilet. Is this a vasovagul response to pain. What can be done to help me??? The diarrhea will come in waves often looking like only water.