Smell after having anal sex and soreness

Patient: Kind of embarrassing but I had anal sex the other day and it was very rough and I was extremely sore for the past 3 days feeling better now but since I have noticed a nasty smell. It is kind of fishy/BM smell. I am extremely clean and have cleaned many times since then.what coukd this be? It was with my partner and we do not have any other partners.