I Have Been On The Nexplanon For Over A Year

I have been on the Nexplanon for over a year and recently had to take a Z pack for strep throat. I took my last pill of the pack on Friday and had unprotected sex on Saturday, and am currently experiencing pms type symptoms even though I no longer get a period due to the nexplanon. I am wondering if I should be worried about pregnancy and if there's any chance the Z pack could have lessened the effectiveness of the nexplanon?