Can anyone tell me what might be causing this?

mace

the past few days my 1 yo has started scratching himself right above his butt and it seem to be annoying him. there’s no rash or bumps, no dry skin, we haven’t changed diapers, wipes, soap, detergent, etc. we’ve tried lotion vs no lotion, a different lotion, and baby powder so far and no matter what we do, clothes or no clothes, he still scratches!

he used to scratch the back of his head when he was younger as a self soothing technique but he doesn’t usually do that anymore unless he’s super super tired, so i wasn’t sure if he was trying to self soothe or not?

he doesn’t scratch anywhere else