Thank you for your question. It is always advisable to be involved in protected sex. It saves you from many infections and sexually transmitted diseases besides working as a birth control measure. Itching penis may be due to varied reasons but as you mentioned about unprotected sex, the most probable reason can be infections. The jock itch i.e. the redness along with itchy groin area is due to such infections. Infection can be fungal or bacterial, the treatment of which depend upon the case. Other reasons can be tight undergarments, allergic reaction towards a particular thing. You are advised to maintain proper hygienic conditions. Consult a doctor and undergo the examination so that the exact cause can be known and proper treatment can be started soon. Take care and stay healthy always.