I have had nexplanon for 2 years and havent had regular periods since being on it and now im having them regularly with bad cramping could the implant stop working early?

The Nexplanon implant lasts 3 years. There is no evidence that they every stop working early. Irregular menstrual periods are typically caused by stress, weight loss/gain, new exercise program or other lifestyle changes that can cause hormonal fluctuations. Talk to you OB/Gyn about these new symptoms and seek recommendations for additional treatment.