No, it's not a STD.
Balanitis is usually diagnosed based on a brief physical examination.
an inflammation usually caused by overgrowth if organisms ( bacteria and yeast).
Antibiotics are used to treat bacterial infections, while topical antifungals such as clotrimazole can combat balanitis caused by Candida
That depends on the cause. If you're not getting relief after 10 days, or if it's getting worse, contact the prescribing health care provider.