Hi,
Thanks for the query.
Straining during passing stools can lead to hemorrhoids.
Usually they lie near the anal opening.
As you are describing a mass near the vaginal opening, more possibly that could be a Bartholin
cyst.
Bartholin gland lies behind the vaginal opening.
The duct of the gland opens between the upper two thirds and lower one third of the
labia minora.
When the duct gets blocked, it will form a cyst.
Usually these type of cysts may not lead to symptoms.
But if the size of the cyst gets increased that can lead to difficulty during intercourse.
And if the cyst gets infected, that can form a
abscess.
As you are having pain, better to consult gynecologist once and get examined.
By examination the exact nature of the lump can be identified and treated.
Take care.