Doctors often diagnose by looking at your symptoms. In most cases, you won't need further testing, and your doctor will prescribe antibiotics.
Sometimes will be used to make sure there is not a blood clot in a deep vein. A or an may also be done to rule out other problems.
If the initial treatment with antibiotics is not effective, your doctor may take samples of your blood and skin to identify the specific bacteria present so he or she can select a more effective antibiotic. Other lab tests usually are not helpful unless bacteremia (bacteria in the blood), sepsis, or another disease is suspected.