weird symptoms

acording to Glow my period was supposed to come on the 7th, it came on the 11th (4days later), which gave me a heart attack, cause I thought I might be pregnant, then it came out strong with big cramps and discharge and then for the next days very very light...but still lasted what a normal period lasts for me 6/7days. it has been 3 days since my period is gone and I feel nausea and cramps...any ideas? I am kind of confused should I test? is it possible? thanks