you are having abdominal cramps and irregular spotting after the insertion of intrauterine contraceptive
these sideeffects are common with the iucd, and will get reduced with in few months..
you have hypomenorrhea
, get one haemoglobin
levels done, if you have anemia, it will lead to reduced menstrual bleeding..
see your gynaecologist for investigation and iron supplements
all the very best..