A realistic Oxycodone dosage?

I've got a question - and a complaint - about Oxycodone dosages.  I'll have to give you some context here I guess. 

I had to go onto long-term disability.  For many years my primary care has been through the local VA clinic.  The VA clinic told me it is their policy to NOT get involved in anything to do with disability claims; they won't do any of the paperwork required.  So they told me I would have to go to another dr. office and find someone who would fill out the disability forms.  So now I have to find someone at the last minute who will not only take me as a new patient, but also get me in to be seen immediately AND be willing to fill out the forms for disability.  Well, luckily I found someone who would do all these things (I can't say enough good things about the staff and the doctor). 

Here's where the trouble starts.  At the VA clinic, I had just been switched from Vicodin to Oxycodone.  I was maxed out on Vicodin and still in a lot of pain.  The VA doc had prescribed me 5mg of Oxycodone, 3 times a day.  It was not helping much.  When I went to this new doc, he gave me a prescription for 20 mg of Oxycodone twice a day, to be taken in addition to the 5 mg scrip from the VA.  I took the new scrip directly to the VA clinic, for one, to follow the rules about not getting narcotics from more than one doc, and two, because I'm a 60% disabled veteran, my prescriptions are free through the VA.  I gave the new scrip to the narcotics nurse at the VA clinic and was told I could fill it locally and in about 10 days the VA pharmacy would mail me the pills.  I fill the scrip locally and am getting some relief, not completely, but better than just the 5mg was giving.  Then, after I've been taking these pills at this dosage for a couple weeks, I get a phone call from the clinic that says the doc won't approve or sign off on that high of a dosage and they are not going to fill the 20 mg scrip.  They said the doc was very upset that I was given that high a dose.  So, I try to make an appointment at the VA clinic and am told that my doc just started a 2 month vacation... So I make an appointment to see a different VA doc.  I get the same reaction from her about the Oxycodone dose.  She acts like more than 5 mg is outrageous, and says that no doctor in the VA would prescribe me more than that.  I told her I had some relief at this dose and didn't seem to be suffering any bad side effects, but she wouldn't budge. 

I then get another phone call from the VA narcotics nurse and am told that the doc said that since I am getting scrips from another doc, I can just fill them privately and that they will not fill Oxycodone for me at any dosage.  Now remember, I was forced to see this other doc outside of the VA system because they wouldn't fill out my medical paperwork, and now they refuse to honor his course of treatment...  I can't afford to pay the $220 or so it costs for these meds since I don't have private healthcare now.