What std has a red sore on penis with no itching. what could cause a red sore under foreskin of penis?

See Below: There are many potential causes of red spots on the penis, most of which are "not" STDs and "a picture is worth a thousand words." The STDs syphilis (painless ulcer) and herpes (tiny blisters) are usually self-limiting. Benign causes: balanitis (fungal); psoriasis, seborrheic dermatitis, lichen planus, contact/allergic dermatitis, fixed drug eruption. Pre-cancerous: Erythroplasia of Queyrat.