I just got a bump on my frontal pubic area under the hair.?

Its about the size of a small gumball. Its right above my gential area like at the bottom of the triangular area between my legs. I was walking through target about a hour ago and i just felt a sharp twinge so I reached down and realized it was suddenly swollen. When i got home and checked it it was red and there was like sort of a pimple feeling on the lump. I've never gotten these before and I was wondering what it was. If it was an std what i should do or if i should go to an obgyn. I'm about 16 and not ually active.