A hematoma means a collection of blood, and if you sustained enough of an injury to the capsule and tissues surrounding your implant, it could have bled into the space around the implant causing a hematoma. This typically makes your breast larger, more painful, and it will cause bruising. Sometimes bruising doesn't appear for a few days, though. If you don't remove the blood surgically, it will "organize" and turn into fibrous scar, and then you will have a capsular contracture and permanent distortion and hardness of the breast. At 4 weeks since the injury, it is quite likely that some of this organization is already happening, and it may be too late. My best suggestion is for you to get evaluated immediately, and if the surgeon determines that a hematoma does in fact exist, you should be taken to surgery as soon as possible. In the even that the blood has not organized too much, it may be possible that with evacuation (drainage of the hematoma) and some postoperative medications like Singular and prednisone to stop scarring and inflammation, it could be salvaged. However, as I said, it may be too late, and you may wind up needing a capsulectomy and replacement of your implant once everything heals fully. I'm sorry to hear that this happened to you, and good luck.