I'm on nexplanon, & taking amoxicillin for an infection. I recently had sex, Will my birth control stop working? Is it likely for me to get pregnant?

Highly unlikely. Nexplanon one of the most effective forms of birth control currently on the market, it is almost as good as getting your tubes tied. No antibiotic except for those used in the treatment of tuberculosis well affect the function of your birth control. The likelihood of you getting pregnant is extremely unlikely. You will be just fine, so if you like nexplanon, recommend it to your friends!
Not likely. Amoxicillin does not interact with the hormone in Nexplanon and will not make your birth control less effective. Some antibiotics increase the metabolism of birth control hormones but amoxicillin is not one of them. If you are taking birth control PILLS though, diarrhea caused by any antibiotic can decrease the absorption of hormones and lessen effectiveness. Nexplanon doesn't have this issue.