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Lack of libido suggests you likely have low estrogen surge.
THis is commonly caused by long term use of IUD.
Pelvic pain can be caused by IUD commonly.
Pelvic inflammatory disease should be ruled out as well.
Ovarian cyst, Uterine fibroid, endometrial lesion are other causes of pain.
Pelvic ultrasound should be ordered.
Hormone levels should be checked including thyroid, estradiol, testosterone, FSH, prolactin levels by blood tests.
IUD should be removed.
Combination birth control pill with high estrogen content will be a good solution.