am i pregnant ?

so i have the nexplanon implant that is going to expire in about a month. my period has lasted for about 15 days now, mostly light bleeding but still a dark red. i woke up this morning with extreme back pain and dizziness.. those are both side effects of nexplanon but is there a possibility that i’m pregnant? my bf and i had sex about a week ago unprotected and i’m worried. am i pregnant?