I scraped my knee pretty badly on the sidewalk. it was a hard fall. I cleaned it with water that night as it was the only thing I had. the best morning I cleaned with peroxide and the next day as well. now, it is not oozing, but it is yellow and solid and still a little discomfort/pain, seeing as it was a bad fall. it's almost like a dark yellow scab. is this infection or part of healing?