by the sounds of things i think its maybe a spot or a cyst and i agree run a hot bath and relax for a bit to see if the heat will draw it out other than that i think maybe ur best to go to the doctors .
Odds are that you have an infection of a Barholin's gland. Although it's hard to know from your description and might also be an infection of a Skene's gland or even a boil. First, try soaking in a hot bath to get it to drain. If that doesn't help and it continues to grow, go to the doctor. They have seen this many times before and will know exactly what to do to. And there's no need to be embarrassed. These infections are common and there is nothing you could have done to cause it. They just happen. Good luck.