I am a 16 year old virgin female. About a month ago I was diagnosed with Impetigo (I had it on my face and chest) and I was prescribed Cephalaxin for 10 days.  About 2 weeks ago I noticed that when I walked or sat down I would experience pain near my vaginal entrance.  I checked and discovered that I had a very small lump/bump (about the size of a pea) right on the edge of the entrance to my vagina that was sore to the touch.  The pain soon went away but the bump remained (I'm not quite sure I still have it, I haven't checked recently).  After that, I don't really know how to explain it, but it kinda felt like I was swollen internally; I sorta felt like something was going to come out of my vagina (usually it felt like a menstrual flow) and I have not experienced any abnormal discharge and I am now a couple days late on my period.  Since then, I have been experiencing soreness, occasional itchiness, and I think I may have minor swelling (or at least it feels that way).  I recently noticed that the tissue around my anus (maybe 1-2 inches outward) has become somewhat swollen and sore and I also noticed small bumps that look like tiny white heads on my labia.  I think the skin around my genitalia is also red/rashy but I am not sure if it is normally that way (I've never self explored before this).  I think I may have a yeast infection but I am not sure.  Do you have any idea what it may be?