Sarah replies:

Have you been to see your health care provider yet? If not, that's the first place to head at this point. It's impossible online for anyone to examine you or to get a clear picture of your overall health and medical history. So heading to see someone who has the qualifications to make a real diagnosis is the best idea. Since you are at a university, you probably have access to student health or a similar service. This is something that an appointment with someone at your university health services should easily be able to address. There are various STIs or other vaginal issues (even something as simple as a Bartholin gland cyst or just an infected lesion) that can cause this type of thing.

But for now, the best thing to do is avoid any activity that will further aggravate the area. So hold off on intercourse or other activities that bring things into contact with the area. Don't poke at it, squeeze it, or mess with it. Try to wear loose fitting clothing and panties. And call health services ASAP and get yourself seen. Letting things like this sit around without being examined or treated is never a wise idea.