I am not against you, but I'd like to hear the answer to this.why would you enter the SAP program if you were taking a legally prescribed medication?
A lawyer may be a good choice for you. Sure sounds like nobody believes your story. I think when one gets upset about an incident that it becomes easy to brush over things, or even forget a few items. You will have to be sure to tell a lawyer the entire truth. Take some time to remember everything the exact way it happened. Otherwise you'll only be wasting your money on him/her.
We've had a few drivers that got help ( one of them twice ) and returned to work. Only one lost his job, but he was allegedly drunk at work when he got in a accident.