reoccurring bump on penis base

ok i am a 21 year old male with a slight problem!!! i regularly shave my pubic areas by request of my girlfriend and about 3 months ago a large bump ( about the size of a thumb tack) appeared at the underside of my penis shaft. i just thought that this was an ingrown hair because i have had them before in the same areas... i tried to pop this bump to see if i could get rid of it. the problem only got worse. for about a week i irritated it and it became red and grew just a little bit. by the end of the week i was able to pop it with a large amount of puss coming out. i thought that all was well and the ingrown hair was gone... little did i know that this thing would come back.... the bump made its new arrival in the same exact spot about the 3rd week of december 08' and is still yet to go away.... i recently popped it again and the swelling went down... however there is a tiny bluish-black spot in the middle where it popped.... i just guessed this was bruising or blood clot.....i just really need some help... can someone tell me what this bump is and if i should see a doctor!!!