Hello, 10% of the people have clear bumps I.e pearl like appearance on the tip of the penis that's normal, people who are having itch below the level of chin might also have genital scabies where there is severe itching and it might cause red rashes on the edge or tip of penis. Unprotected Sex can cause syphilis which appears as a red ulcer, so I suggest you to consult a dermatologist to ruleout this things.