period talk need advice please

okay so im an irregular for my period and i usually only last about 4 1/2-5 days well this month i started an i had my period for 2 weeks straight im not on any type of birth control or anything but now just today i started my period again. iv never really had a period two times in one month. Has anyone else experienced this before? Or does anyone know if its fine an normal or should i be concerned an go see my doctor? thank you in advance