Medical cannabis for insomnia and PTSD

Patient: I wish to get prescribed by my primary physcian not medical marijuana doctor for medical cannabis prescription for PTSD, chronic knee pain, and Insomnia. I line in CA and dont prefer to take the Narcotics they prescribe me before but I need help and I know cannabis works. Can this happen?.

Symptoms: Insomnia, joint knee pain, loss of appetite, jumpy at loud noises,