Help! What is this....sex after getting on birth control

I just got on the implant (nexplanon) 3 days ago and was told to use condoms for the first two weeks this is my first time ever taking any sort of birth control. Me and my boyfriend had sex already 6 times after me getting on birth control. We had no complications but on our 7th go I started feeling weird when he put it in. Sex didn’t feel good almost uncomfortable and this came out on the condom mid way and I’m concerned what it may be. If it’s possible it’s a affect from the birth control. Has anyone had this problem ?