Hi So I Guess It Started About A Week Ago

hi so i guess it started about a week ago i thought i had started my period but i am on nexplanon so when i do have a period they are always different this is the lightest one i have ever had then i started have horrible headaches now on day 7 i am still bleeding and i am having pain on both sides of my lower stomach/pelvis area i also have a darker color of urine should i be worried ?