If I eat three meals a day and sleep 8 hours I will wake up and have breakfast and some water that will create a bowel movement. But If I don't have breakfast It will not create a bowel movement unless I eat more food. I have a bad smell coming from my rectum and I have lower abdominal swelling or bloating.
You need to see a Gastroenterologist to be checked out as this is their specialty. I don't think it's anything serious. It sounds like IBS (Irritable Bowel Syndrome). This is easily treated, and not serious. Take care.