What Happens When I Taper to a Lower Dose?

I am wondering what is happening in my body (serum levels?, opiate receptors?) when I get to the next lower dose.  The drug I am tapering from is Opana ER.  I have just been able to have 1 day at 25mg (a 20 mg ER and a 5 short-acting).  I take this dose 3 times a day.  I wake in pain on most days.  At this point I don't know if the pain is worse because I am waking in withdrawals.  After taking the Opana I start to feel better.  I am just wondering how the body adjusts to the next lower dose, why it is way harder some days than others, and any tips on making these transitions.  Do some of the opiate receptors die?  Surely more grew as I took more and more Opana, right?
Thanks!

[justsaynotodrugs]

          When you take these meds your body and mind become fixated on the doses causing you chemistry to go out of control.  Then you cut back and boom all is not well a good taper is lowering the dose slightly then later on you can cut back a little more the Thomas recipe is on the page you can pull it up and it will tell you what you need to help the wds.    hang in there.