What Causes Lump On Vagina Which Oozes Puss?

i have a spot like lump on my vagina, it was quite big and when squeeed a puss came from it making it smaller, however has stopped coming out and is still viable and is making me uncomfortable, what is it, i am too embarrased to go to the doctors, or will i have to?

i am 18 and in a long term relationship