3week old runt bard rock

[Maddiesmaw]

the others are growing by leaps and bounds ... The runt has continued to have the "pasty" issue going on and it almost looks bloody now! We are new to raising chicks-Haven't lost any of them and don't want to lose her either. Have tried to wash buildup away but really hard

 

[Dutchgirl]

Is this chick a lot smaller than the others? If so, has it grown much at all?
Some chicks just seem to have a bad pasty butt problem. I'm not sure if it's actually something wrong with them or not.