I have been taken hydrocodone for a back injury pretty regularly.?

I was just getting ready to get off of it and give my body a rest from the narcotics when I came down with the shingles. They are extremely painful and when I went to the doctor he gave me oxycodone for the pain because the hydrocodone was not working. This is about my 3rd day without hydrocodone (taking oxy's for pain from shingles). However I almost feel like my body is withdrawing from the hydrocodone. Is this possible even though I am still taking a opioid. Or are these to drugs different and therefore have different effects on you causing you to have withdrawals for the one.