What does the pain feel like? Is it sharp or is it dull?
It can be pinching of skin or organs from a weak spot in the abdominal wall.
Try making sure your stomach is as empty as it can be and see if that helps. That will reduce inner tissues from being pinched up against outer ones.
A few time I got a sharp pain in my right abdominal side, when squating low. It doesn't seem to happen anymore. It may have a plastic belt buckle to my shorts, but it didn't seem likely just didn't feel like it could have been it. It happened on 2 squatting days 1 week right after another, during each of those days it did not happen on every set, but at least once or twice each time. It no longer happens, I'm not sure if I've worn those same shorts since then, (actually I will be wearing them tommorrow, I'm still not convinced its the plastic belt buckle on them) I pretty sure my pain just went away, which will hopefully be the case for you.
Can you reproduce the pain at will? I.g every time you go down below || yourguaranteed you will have that pain, or only a chance of it.
btw scared the shit outa me when I had it, I was like wtf, hmm wtf does a hernia feel like hmm wtf is a hernia god damnit I'm dieing wtf is going on. NOOOO!
(wtf = what the fuck)