Hi.
Thanks for your query.
Read and understood that you are getting pain/cramps in the lower abdomen.
Since you are on Implanon,
pregnancy or ovulation pain is not possible.
There are other reasons of pain in the lower abdomen like:
PID- pelvic inflammatory disease
Enteritis
Salpingitis,
appendicitis
and so on.
I would advise you the following:
Get a clinical evaluation and physical examination by a
General Surgeon,
Ultrasonography of the whole abdomen including pelvis.
Tests of blood, urine and stool to see any evidence of infection.
Get a course of an antibiotic,
metronidazole and anti-spasmodics so that you get a complete relief, rest of the treatment as per the reports of the tests.
If there is a surgical cause, get operated.