Concerned or not to be ?

Ok so my periods always been normal all my life but until last year October I had a normal period and after that I stopped getting them! Negative pregnancy tests and all. So when February came I got mine again but it was lighter then usual but lasted about two weeks. And every month until now been lasting 2 weeks and here I am today I been bleeding over 2 weeks. Does anybody know what can possibly be the cause ? 😕 should I be concerned could it be something serious ?