choking during sex bruise? almost looks like a hickey

so my boyfriend and i have been having sex together for like two years and he’s always choked me pretty much from the very first time. for some reason recently the last couple times he’s done it i’ve gotten a bruise or something, it almost looks like a hickey just very diffused i guess. and this has never happened before but it’s happened the last couple times, like the first time he was doing it really super hard and i didn’t tell him to loosen up and we noticed it and we were both like well that’s weird maybe it’s from doing it so hard? and then the times after that it seemed like it happened even when he didn’t do it super hard, so i don’t really know. i don’t know if there’s anything i can do to stop it from happening or if i should be concerned that it’s like a blood clot or something like that.