The severity of cramps varies widely from woman to woman and even between the same woman's periods. Some have cramps that are barely noticable. Some have crampes that are excruitating. They may also have weakness, chills, and dizziness. Spasms of the leg and abdominal muscles occurs with severe cramps.
Secondary dysmenorrhea is when cramps are due to an actual disease, such as endometriosis.
The severity is NOT a clue as to whether or not the cramps are due to a disease that needs to be treated. Primary dysmenorrhea is more likely in women whose first period was early in life and those who have heavier flow. It is common in the first year or so of a girl's menstruation, no matter when she starts. Secondary is more likely when the problem starts after the age of 25, or when there are other symptoms. Still, the only way to know is to be looked at by a doctor.