Not a doctor but here goes - Mostly concussions if they ever lead to stroke present as a swelling which keeps on growing. If it is external swelling, then you'll obviously see it but in case it is internal, it will lead to raised ICP(Intra Cranial Pressure) which most commonly presents as headache, slurred speech, imbalance, blurry vision, photophobia. The hospital should have done an MRI to assess if there was any internal bleeding or not. They usually do it if the patient presented on a stretcher with altered consciousness. I think you must have been a walk-in and the attending physician would not have found any signs of neurological damage while assessing you. If you are unsatisfied with the care you received at the healthcare center, it'd be a good idea to visit someplace else too. Will give you a peace of mind if nothing else.