What you describe could be symptoms of a number of conditions; only a doctor can examine you and give a diagnosis. Here are some suggestions to consider until you decide about consulting a doctor.
- Since the red patches appeared after sex using a condom, is it possible that you are allergic to latex? If so, there are alternatives to latex condoms.
- If you don't retract your foreskin regularly in the shower and wash that area, you might have balanitis. If you do wash your exposed penis head regularly, you might have a reaction to the soap. In that case, you can keep your glans and foreskin clean by washing them regularly with just running water and the friction of your fingers.
- You might have a fungal infection. An over-the-counter cream containing clotrimazole usually clears up this condition if you follow the directions that come with the product. In Australia, you can buy these creams at supermarkets and pharmacies.