What Causes Smelly Sludge-like Bowel Movement Post Oral Sex?

For almost a month now, after engaging in anal sex for the first time, My stool smell absolutely foul. And is mud/sludge-like quite often. I m female, 43, 5 2, 215lbs (30 of which have been gained in the last two years due to an accident) I IBS, hyprothyroidism (.137mcg) workout (trx, yoga, personal trainer, paddle board) a couple times a week. My diet isn t always at par as to where it should be. I have eliminated coffee to the weekends only. I don t drink a lot of sweets (juices or pops). I drink socially, and only ever 1-2 glasses of beer/wine. MY question is, should I be concerned of an infection from the anal sex we tried early september, or concentrate more on my diet, and adding more greens. ( i can t eat anything from the lettuce family- is a trigger for the ibs)