You need to speak with a personal injury attorney, who can evaluate all the facts and details for you. The short answer is, IF you suffered harm due to a lack of medical attention and it would have been reasonable to have provided it, then you may have a lawsuit. If you did not suffer harm, you effectively have nothing to sue over, though you could certainly try to raise a complaint in some fashion (ask yoiu lawyer how best to do this); or even if you did suffer some harm, if under the circumstances it did not appear to be urgent (e.g. it was not credible that you needed it immediately), then there also might not be liability.More to the point, if you were slammed headfirst into a car by 5 officers, you may have been the victim of excessive force or brutality, and that's something else to discuss with your attorney. Good luck.