Sores on the thighs are mainly caused by a decrease in immunity or a trauma that causes a bacterial infection, which can result in a relatively large boil. The sore is red, swollen, and painful, and the skin temperature is elevated, which can cause a generalized fever in severe cases. You can order antibiotics such as levofloxacin hydrochloride injection or clindamycin phosphate injection, and apply topical fusidic acid ointment or compound polymyxin B ointment twice a day, and apply a wet solution of Revnor. Twice a day for twenty minutes. When the inflammation decreases, the redness and swelling subsides, and only tiny boils appear, you can switch to oral azithromycin capsules, or roxithromycin capsules for treatment, and avoid using your hands to squeeze the sore during treatment to avoid aggravating the infection.