Wow, that sounds like your pal is in pain. When a dog is bitten on haired skin, it is often diffcult to see the full extent of the wounds. If the red spots are below the level of the bite, they may be the result of bruising from the bite (blood from the bruise may be migrating down via gravity) or it could be that there is infection developing and manifesting itself as these red spots. It is almost impossible for me to tell you what is up without a photo or better idea. The biggest worry I have is that he is not feeling better after three days and you are seeing additional symptoms, rather than improvement. Please seek veterinary attention if he is not better by the time you read this, OK? Hope he's feeling better soon.