Based on the information it seem like you are having sharp pain
in your breast and not it went away. Still you have a knot in top side of your breast.
It seems like it might have a association with menstrual cycle and it comes and enlarges the know with first 15 days of cycle and it would cause pain, after those 15 days the knot goes down in size and stops hurting. It needs to be checked.
If it does not changes according to time and the knot stays the same.
1) I advice you to have it checked with near by surgeon.
2) They will require you to have mammography
to check the cause of knot.
Thanks for the query.