Is it painful and tender?
Most common possibilities are;
1) submucosal lipoma and
2) dermoid cyst.
The possibilities for the lump you have described can be;
1) Inclusion cyst
2) Gartner's duct cyst
All of them are benign, so indication of removal is discomfort, annoyance or pain. An inclusion cyst (the commonest structure) is a small encapsulated fluid filled structure due to embryonal or traumatic implantation of epithelium into another structure. The treatment is surgical removal.
With the discomfort, it is causing an evaluation by your doctor would be prudent. Read the resource;
Please feel free for your follow up questions.
Very unlikely that this lump was formed by the trauma.
It is pleasure assisting you.