Possible chemical pregnancy

How can I tell if it truly was a chemical that I lost vs just having a heavier than normal period (it did have small chunks too)? AF came a week late, but just before it came I started getting sick to my stomach and cramping more than usual and getting headaches. It only lasted 3 1/2 maybe 4 days usually my periods last 5-7 days. Sorry if there was any information that was a tmi.