"I started a few months ago due to a chronic pain issue, and I have to say I am/was surprised by the benefit."
I've been through a lot in which marijuana helps with. I had a Brain Injury from a car accident, and then a sub-sequent accident caused me to seek a Lawyer because of pain, who sent me to a doctor who gave me Neurontyn, I didn't like it, my Lawyer sent me to another doctor who experimented with me.
Long story short, for the past three years, after all the medications failed, marijuana deafens the affected area and I can only feel where I was injured (obviously, a permanent injury), but no pain. I wake up in the morning with slight pain (but only sometimes), which goes away "miraculously" as I start my herb-smoking schedule. The prescription medicine numbed it. So, that's just some background.

"are there any studies that focus on potential side effects of pot w/ prescription meds?"
I've been looking for some, but no there are none, trust me.

But be careful with mixing them because it may cause a "nervous" reaction.