It's a prescription. You won't be able to get it unless your doctor writes you a prescription.
Your best bet would be to research what the drug is used to treat and then book an appointment with your doctor and explain that you have all those symptoms.
Whether or not the doctor writes you a prescription is at his discretion but if you really want the drug, that's going to be your best bet.
I doubt you'll be able to find it on the black market.