i need an advise

it happened that i had an unprotected sex with a girl that i did not knew too well and since that day i have been thinking of what i have done and this happend passed 3 weeks and last 3 days i notice that i had a problem ie i noticed that one pimple appared on the hip of my panis and not only that the nest day a kind of pimple came within the ridge of my panis and this one made me to believe that i have been infacted ,and the one on the ridge is not excertly like pimple because i can see that it has some liquid inside ,even today i notice another two pimples right in another part of the hip of my panis ,plz i am so ashearmed of my self ,i dont know what to do or how to go and show this to the doctor .i need some advise