I too had a stereotactic biopsy but I am about 3 1/2 weeks out. I also had and still have a hard like knot about the size of a grape, so I called my surgeon around the 2 week time and he said that was normal and some women it can take up to a month before the breast tissue feels soft again in that area, in fact it has become smaller from the 2 to 3 week period. I also had twingy like pains kinda all over the breast but they are now slowly decreasing as well. It's basically just scar tissue and fat filling into the biopsy cavity, I had 12 samples taken so maybe people with less have an easier time. I did not feel a thing during the biopsy so I cannot help there.....
If you do have a bad looking bruise or it looks like blood pooling under the skin I would def. be seen again, just call and get a nurse to return your call and explain to her whats going on- that way you don't have to go back unecessarily.
think you may need to see a doctor. If there is still pain after 2 weeks, you may have a hematoma (an area where exsanguinated blood has accumulated). This is generally painful because of the space it occupies. Generally, the body absorbs small hematomas but if it is large, it would need to be drained surgically. Inspect your breast if there is a sign of a bruise over the area of the biopsy. Steretactic biopsies though are associated with a very low risk for hematoma (about 1%) so it may also be some other problem. It is also possible that the pain may only be from your oncoming menses, there may be some areas not fully healed yet and the engorging tissue surrounding it may be exacerbating the pain (although after a 2 week period, this seems not too likely). I would advise though to see the doctor – you could also have an ultrasound done to examine the breast and this would not be as painful as the mammogram.