Complaints
Physical or mental discomfort or pain is called a complaint. In the case of a complaint, it is not always clear what causes it. An example of a complaint is back pain.
Diseases
When we think of illness, we often think of a physical abnormality, but a mental abnormality is also called a disease. Due to an illness, a person may be or become limited in his or her functioning. Or die earlier. An example of a disease is diabetes.
Disorders
A condition is an abnormality of the healthy physical or mental state. An example of a condition is a broken leg.