What type of attorney do I need for police brutality if I’m only 19 years old?

I was walking with a friend going home around 1 in the morning. Apparently so the cop that pulls next to us instead of seeing if we fit the description to whoever he said was breaking into cars he automatically decided to harass us by asking questions, I don't care I don't have nothing to hide but I do know my rights. I go ahead start asking him why is he picking on us. And that's when he decided to punch me on my chest so hard I fell. I ran because I got scared and that’s when the same officer and others that were called beat me up I can't even talk or breathe right. They tried charging me with stuff but the judge didn't buy it and dropped everything and let me go. I have never in my life have been arrested not even a ticket. I want to file a law suit a big one. This abuse has me in so much pain that my mommy in the morning is taking me to the hospital.