Hi dEar , As per your query you have ringworm under your knee . Ringworm is a common fungal infection that can cause a red or silvery ring-like rash on the skin. Most ringworm infections are mild and can be treated using a pharmacy antifungal cream. Sometimes skin is irritated or broken, it can lead to other bacterial infections, which may need treatment with antibiotics. I would suggest you to consult dermatologist for proper examination . Doctor will examine physically or order skin tests . Doctor may prescribe oral or topical anti fungal medicines like fluconazole or terbinafine and corticosteroid cream . For now wash it with warm water , keep it clean and prevent it fron contamination . Hope your concern has been resolved. Get Well Soon. Best wishes, Dr. Harry Maheshwari