Thanks for the answer, and your worry is right as you might have got some fungal bacterial infection after having sex with your girlfriend. In other cases, red spots are also caused by yeast formation. You need to consult a doctor, but the primary initiative you can take is to have a complete hygiene and cleanliness. Clean your pubic area thoroughly with medicated soaps and apply some anti-bacterial, anti-fungal cream. Also it has been seen that unless the fungal effect has been completely cured the problem goes and reappears time and again. So you need to be cautious about the medication, cleanliness and hygiene.