Cop has mind made up before hearing anything

I am a photographer and last week I was shooting an event basically in the middle of nowhere, 4 ½ hours away from home in an area where I had never been before. After the event (@6pm) I was driving to a motel and the GPS on my phone wasn’t working right so I pulled over on the shoulder to get my bearings and try to fix the gps. A cop pulled up behind me and asked me what I was doing, etc. I have a number of health problems and have to take quite a few prescriptions. I've been basically taking the same medications for at least 12 years and never had any problems. I take them only as prescribed, don't use other drugs and don't drink. When he saw my medications (which I keep in a little bag along with Tylenol, aspirin, ibuprofen, etc.) he told me to get out of my car, asked a few more questions and then he suddenly handcuffed me and arrested me for DUI. After being driven for about 20 minutes to a police station I was driven to the Dept of Corrections where I was fingerprinted and all that sh*t and then in the morning shoved out the door without being allowed to ask anything. I had no idea where I was and there was nothing around for at least a mile. Plus my wallet was minus the $200 that was in it the night before and my cell phone and everything else was in my impounded car. I had the impound slip but in the middle of nowhere, never having been there, with no cell phone or anything, the address might as well have been on the moon. I’ve been raging ever since – I’m 56 years old and have never had any run-ins with the police, the only thing on my record is a couple of speeding tickets and an at-fault accident, this is such BS!