There are many well documented associations between emotions and physical symptoms. We are whole, complex beings that cannot be separated into body, mind, and spirit so it makes since that problems in one area will impact another. For example, there is good evidence to support the high incidence of abuse history among those with irritable bowel syndrome. Those with chronic pain often have coexisting depression or other emotional stressors.
The reason for these connections is because every pain sensation that the body interprets has the potential for entering into the limbic system of the brain when it is being processed. Additionally, hormones associate with emotional stressors (e.g. cortisol) change the way information is processed and can lead to amplification of pain signals.