Sex on nexplanon

So I had sex the other day with someone for the first time in four months. We’ve been talking for two months and decided to do it the other day. I’m on nexplanon and it’s messed with my cycle a lot like I’ve had light bleeding and brown discharge for about a month now. It stoped so we had sex. He came inside of me and we didn’t use a condom cause we had both been tested. He’s a lot bigger than the guys I have slept with in the past. Now two days later I have a light pink discharge and tenderness. I assume the tenderness is from having someone a lot bigger than I’m used to but I’m not sure about the pink discharge and whether it’s a side effect from my nexplanon or it’s something I need to worry about.