Pain in lower abdomen

Me and my partner had some great sex midday Friday before work and later on that night I came home and was having severe pain. It lasted all the way til today which is Sunday Nov 16th. It feels like I'm having my period because the cramps feel the same but it's not my period because I just came off my period that lasted 6 days and usually it lasts 5. Can someone give me answers on why I'm feeling this way?