Hi, I can understand your concern for painful bruises on thighs. In your query you have not mentioned your age, sex and other relevant details so that the exact cause could be found out. In most of hte circumstances these bruises are normal in its appearance without any cause. You can go for your routine blood check up concerning mainly to bleeding time, clotting time and platelet count. If these are normal then there is o need of worry. If these comes abnormal then you should preferably meet a physician. The marks will fade by itself in next 14 days, so there is no need to apply anything over the same. Hope these information will relax you. Take care.