While it's always worth seeing a doctor if you have digestive problems, they may surprise you by finding that the problem's not in your belly: it's in your brain.
Your gastrointestinal tract is incredibly sensitive to your emotions; they can make you feel nauseous, lose your appetite, or crave comfort food. When you're going through a period of severe, chronic depression, you may experience cramping and other symptoms that would normally be associated with irritable bowel or Crohns disease.
Like the emotional symptoms, the physical symptoms of depression are rooted in the nerve pathways which are used by neurotransmitters serotonin and norepinephrine. From their base in the brainstem, these pathways travel to the frontal cortex, where they help regulate thinking and mood. They also travel up to the brain's hypothalamus, where they regulate processes like eating, sleeping, and reproduction. As well as traveling around the brain, these pathways also make their way down the spinal column. There, they're responsible for allowing us to ignore the sensations that result from everyday bodily functions like digestion. When you're depressed, you lack serotonin and these pathways don't function properly - so those routine, everyday sensations end up being felt, and they're interpreted by the brain as painful or uncomfortable.
The relationship between digestion and depression is incredibly complex (eg, digestive disorders can cause depression) - so it's important to get checked by your doctor just in case something bigger is going on.