Question for momma's with boys! Need help 😊

My son is 6 months old and was circumcised at birth. Today while changing his diaper, I noticed a small red line (maybe a cut?) at the base of his head. Anyone else's son ever get something similar? What did you do/what was it? His seems to be getting redder, not sure if I call his doctor or not. I don't know how he would have gotten cut down there other than maybe by his nail since he's recently discovered he has something down there and tries grabbing it at every diaper change lol.