Pain can be a side-effect of stress:

Aches and pains can be a body’s physiological response to stress. Luckily, massage is an excellent way to decrease these symptoms and reduce stress and promote relaxation and repair in your body. To learn more about stress and how it effects your body check out this awesome TED ED video clip: https://ed.ted.com/lessons/how-stress-affects-your-body-sharon-horesh-bergquist