Oxycodone has been available as a generic for quite some time, not sure what patent is expiring.

Opiates and Benzodiazepines are controlled substances which are abused and resold for recreation. Doctors are weary of drug abusers shopping for Rx and leary of the DEA so they are not likely to prescribe just because you ask. Some doctors even make it a policy to never prescribe benzodiazepines.

A pain doc needs a full history and justification to treat you.