I had scraped my arm on a rusty bob wire fence earlier and was bit by something all on the same arm, now its got red splotches and is very sore? What should I do.

See your doctor. Sounds like it may be infected, or it could be something worse. Rusty fence, and a bite (you don't say what bit you) could indicate something far worse than an infection. When was your last tetanus shot?

Either way, it's time to see your doctor.

Infection, blood poisoning, or worst. Cuts and scrapes from rusty items can cause serous even fatal at time issues.