Bleeding after Intercourse w Nexplanon

I have have the nexplanon implant for around 4 months now and have had relatively little spotting or bleeding. About three nights ago my bf and I were having sex and he proceeded to make me orgasm (oral) and then shortly after realized I was bleeding so we stopped, I bled a bit the next day and was fine all day yesterday and today. Tonight we repeated the process and after I orgasmed we continued to have sex and once he finished we discovered that I was once again bleeding. I'm not sure if this is common or if it's something that warrants concern and maybe a doctor's visit? We are both STD and STI free, so my main concern would be with the hormones itself. If anyone has experienced this or something similar let me know!