Hello,
From your symptoms,it looks like a Bartholin's abscess or cyst. There are glands in the vaginal lips called Bartholin’s glands. These can become painful and swollen, and an abscess can form. This often causes blockage in the main duct from the gland, and a cyst develops. This is felt as a painless, hard swelling.In such cases, antibiotics may be helpful, or surgical treatment might be required.
Other possibilities are sebaceous cysts (accumulations of secretions that can occur Fanywhere on the skin or mucosal surfaces), lipomas (fatty deposits) ,fibromas (fibrous tissue deposits) or viral warts(small raised pimples to a mass of large, cauliflower-like growths. The virus that causes them is passed on during sex).
An examination by a gynecologist will be the best as it is only after an examination that it will become clear what the swelling that you have noticed is due to.
I hope that helps. Take care and pls do keep me posted on how you are doing or if you have any additional doubts.Kind regards.
Bartholin glands inflamation.May be you will need a course of antibiotic.