I agree, take him to the vet. Last year we were letting our one cat outside and she got into a fight and came back limping a little. We found a small wound on her and cleaned it out with peroxide and didn't think anything of it. She seemed fine for a week or so, then started limping again. We realized her leg had swollen up overnight to twice it's size so MIL (who is basically a vet tech and experienced with animal care from owning a farm) came over and we held her down and drained the leg. We did that for a few days and realized it wasn't helping.
We took her to the vet, and he had to put her under and literally cut her wound open and swab the infection out. It was deep in the muscle. He said we did what he would have done to begin with but the bite/scratch was so deep the peroxide wouldn't stop the infection because it couldn't get to it. Total vet bill was over $600. She's fine now, but she will never have full use of that leg. She still limps, and it's worse when it's damp.
What she needed in the beginning is immediate vet care and antibiotics. We thought it was just a superfacial wound and not serious...but it wasn't.
I would take him to the vet as soon as possible just to make sure there isn't serious damage.