A red bump on penis head (I am circumcised )

Hi all,I have a redish looking bump on the tip of the penis, on the head towards right side.I am really scared, I am 24 and am a virgin. Although i have a girlfriend,It appeared after I mastubrated, initialy it was small but in next few days it has grown a bit.I am not in any physical contact with my girlfriend for last 2-3 months as she moved to different city for work.Although growing of the bump has stoped, I am on ethromicine (may be wrong spelling)I really dont know what it is, I went to the doctor he prescribed a homeopathic medicine, when I asked him what it is, he said most likely to be a pimple or a cycst..Cyst are supposd to be hard right??mine is not really hard.On the note it is painless,In the next few days i will visit an urologist,Any input will be helpfulThanks