Thanks for all the info, guys. Really appreciate the help. And actually yeah, I have just started teaching myself low bar squats recently, and it only just occurred to me today it could be that - a kind of tendinitis(?) from incorrect squat technique.
I watched a Rippetoe video on bar placement and grip a couple of hours ago, and I think I've had the bar too low, my grip too wide, and my elbows too low. D'oh.
The pain struck on the negative (of the bench press, first rep), towards the lower part of the RoM. But it continued for the rest, which wasn't much - I actually went to full failure quite embarrassingly (didn't exactly drop it, but even so), but thankfully, had a spotter for once (knew I might need one).
I did bench first, and the pain didn't seem to affect either the pulling or the squatting (oddly). The pain wasn't even really there much for those.
It's subsided before even a full day, again. But I'm aware that I might still need a break, or whatever. I do tend to be "stoic" about most shit IRL.
But if need be, I'll do whatever it takes.
edit: I have also been doing heavy chins (for my strength levels), going for sets of 5, then 5+. Would that be too much intensity, potentially? I do bodyweight pullups and chins as well, but maybe it's another risk factor.