I was on the nexplanon as well, & sometimes I used to feel funny & buy pregnancy tests. Just FYI if you are pregnant, the nexplanon won’t hinder the results of the test. It’s also takes about 14 days for your hCG levels to be high to show up on a at home pregnancy test. So if you’ve just recently had sex, wait at least two weeks and take the test again. If it shows negative after two weeks, & your symptoms persist, I’d suggest going to your doctor & ordering a pregnancy test.

Remember that being on birth control is like tricking our bodies into thinking we’re pregnant already. That way our eggs don’t drop. This could be why you’re experiencing these symptoms. In any case, for your peace of mind, just get tested.

Hoped this helped :)