IUD difficulties!!

So I finally came to a conclusion that kids just arent for me right now.. As a result, I decided to get a IUD! I went with a 3 year brand made for woman who havent given birth ( smaller form). It was beyond painful but quick, its been over a week, im still bleeding, the bad cramping has become minimal but when they strike its bad, but ive been having sever headaches?!! Anyone out there have any info or simalar stories with the IUD?!