Mild cramping in the first day or two is common and usually reflects the uterus contracting as its lining sheds.
Pain that keeps you home from work or school, that does not settle with over-the-counter pain relief, that worsens year on year, or that arrives with heavy bleeding is a different thing. It can point to endometriosis, adenomyosis or fibroids — conditions that are common, treatable, and frequently diagnosed late because the pain was accepted as normal.
The average delay to an endometriosis diagnosis is measured in years, and a large part of that delay is women being told, and coming to believe, that this is simply what periods are.
Track what you experience: how many days, how it responds to pain relief, what it stops you doing. That record is what turns "bad periods" into something a doctor can act on.