What Causes Open Sores On The Genitals?

I am a 21 year old female. 5'7, 115 lbs. I recently developed open sores on my genitals. About 2 years ago I was diagnosed with HPV genital warts, but these sores do not resemble the warts I had at that time. I have been reading online about genital herpes & syphillis, etc and saw that with herpes there is typically a pimple like growth that bursts then becomes an open sore, but I have not had that. These were just small hard bumps that became open sores within about one day. They are painful and are constantly oozing. I have also had muscle pain in my buttocks & hamstrings for the past 2 days. I dont know if this is related or not. Please help!