Thanks for using JustAnswer.com, I'm Dr. Dan and I'll try to help you.
If you have a smell of dead flesh and something that looks like a maggot on the wounds then the vet is unavoidable. If the flesh is dying it needs to be removed from the body before it allows the spread of the disease. Also, it sounds like the antibiotic you are using is not working if dead flesh is being produced. The feed store will not help you. You need to get to the vet and soon before this small problem turns into gangrene which can become fatal. I hope this helps, best wishes.
For many antibiotics the time to peak blood effect is 1-5 hours so yes the antibiotics are likely working. If the bacteria are suceptible to the drug you have and the drug you have has good wound and skin penetration. Many times in bite wounds the damage to the tissue done by the bites cuts off blood supply to sections of the tissue around the bite. When we get massive bite wounds in our clinic we take them to surgery to remove this devitalized (no blood supply) tissue. The reason we do this is that tissue with no blood supply cannot get antibiotics delivered in any meaningful way. As long as this tissue remains it is a safe harbor to for these bacteria to hide and contiue to infect the wound and continue to make it worse. When the dead tissue become colonized and begins to "spread" that is gangrene and that's very bad.
Thats ok, but if anything changes or the dead smell lasts any longer than 24 more hours you need to see the vet.