Hi Sweety,
I haven't been around here in some time but happened to check in and saw your post.
I have been living with CP now for almost 9 years due to a wide range of issues.
I have been on many different pain medications and have done a lot of research, pain medications are just like any other medication what may work for one won't another and what may seem a high dosage for some is low for others.
Some doctors wont' do BT meds as they believe your LA medication should be effective enough not to need BT meds, also some medications won't mix with any others.
As for Oxycontin when I was on it I tried several BT meds, now though I am on Ms Contin and it works well on it's own for me.
First off I would talk to your Doctor about this and she what he advices also there is a really good "pain management forum here you might want to check out.
I hope you can find something that works for you soon and get relief.
Good Luck,
Linda