What Causes Delayed Period Along With Stomach Cramps?

Hi sir..m 27f just married..7th nov..having sex since mid dec..I was supposed to have periods by 7th Jan..haven't have dem yet..since a week m experiencing cramps..initially I Thot dey were periods cramps..but till now no periods just pulsating abdominal cramps.. Mostly one meftal helps with d pain..but m worried now..plz provide suggestions