You have a recurrent bartholin gland cyst
. What you are describing is quite large, and I am guessing that given how fast that it has progressed, is likely quite painful as well.
Sometimes, the fluid in the cyst can become infected, called a Bartholin Gland abscess
. Given the acute nature of your problem, I think that it requires immediate attention. It can be drained and you can be put on the appropriate antibiotics, hopefully before this becomes a surgical problem.