Found a grape size lump on inside of vagina?

Bartholin's cyst: Bartholin's cyst is a likely diagnosis. These come from glands at the 5:00 and 7:00 areas of the vaginal opening. For different reasons they can become blocked and fluid will accumulate. If the cystic area goes back down quickly it's ok, but otherwise see you gyn for evaluation.

Exam: Could be lots of things including cyst, fibroid, infection, impelled object or healing tear. Only visualization will give you an answer so get a vag exam.