Ds had 2 nasty grazes on his knee from falling on Tarmac. I bathed them in the bath within an hour and tried soaped them well. Then when he got out of the bath I noticed there was still dirt in the grazes. Used some boiled salt water to try and wipe the rest out but obviously very uncomfortable. Then put on lots of savalon. This morning I can see spots of black in the wounds. Will it work out naturally or do I need to do more scrubbing?