Falsely accused of possesion and Fasle statement from police officers

I was charged with possession of oxycodone and am facing jail time for a felony 5. When I was arrested I was not in possession of the pill it was 15-20 feet from me, the police officer made a false statement that I had purchased it at a bar I was at earlier that night, and in the same statement he said that I had a prescription for them, duh if I did why would I buy one?? The point is it was not my medication; it was not on me it was not near me, they said that they saw me throw it, but it was 3 am and on a country road, I did not throw it. But it their word against mine. I have a public defender that has gotten people off of murder charges but is not worried one bit about my case. He has not attempted to get it reduced, he has not said anything about the false statements made by the officer which contradict themselves, and he has not brought up the fact that when I was arrested I was not charged with possession; it was 6 months later under a secret indictment. The original arrest was for concealed weapon which I am currently on probation for. It seems to me that they had to take 6 months for them to figure out how to charge me for something that I am not guilty of before they could do it. I need advice on what I can do about this and if there is anything at all I can do about the false statements made by the officers. I have been out of trouble for years up till all of this stuff happened and because of it I have lost my job and am facing up to 5 years in prison over, pardon my French, bull****.