My period last month was 2 days with unbearable pelvic pain, this month had 2-day period with headache & back pain, usually have 5 day pd no symptoms?

May be normal: It is common for the nature of a woman's periods to change over time. Sometimes there get better and sometimes worse. If this is just a normal progression for your periods then the symptoms may persist and could likely be improved with medical treatment - your doctor would be able to help you. If there is something amiss (infection, endometriosis, etc) you will likely get worse, then see your Dr.