I def wouldn’t pick it it could be painful but I could clean it with warm water and maybe put some ointment on it
This happened to us too bc of moisture buildup - drool, spit up, sweat etc. cleaning daily and adding ointment cleared it up
If it is skin then don't pick it off. And since you can't tell if it's dirt it skin I would probably be more cautious and not pick it off. Use some warm water to irrigate the area and see if any of the debris loosens. Than apply aquaphor. If you keep applying aquaphor religiously, any crusting that isn't living tissue should come off. If it is a rash it may be something your pediatrician needs to assess.
We had the same thing! I asked the doc it just has to do with sweat, spit, and dirt getting stuck. We just wash extra good behind our ears now. :)
My baby had the same due to me not cleaning it during bath time just during his bath wip with a rag with warm water and after his bath put some aquaphor