I began taking a medication for my very sore back. Every time I try to cut down, I feel achy and miserable. I never imagined my doctor would give me a drug that would be addictive.
Although only your doctor will be able to tell you for sure, it doesn't sound like an addiction but, rather, that you've become dependent on the medication. The difference between the two is that if you have an addiction, you have to have the medication right now, immediately. You need it and you miss it when you don't have it. Obtaining the drug and administering it is just as important in the high.

For people who are dependant, they have a physical need for the drug. Their pain gets worse if the medication in their system is lowered and they may develop signs like a runny nose or muscle aches. These are physical signs.

The best thing to do is to go see your doctor and discuss your concerns.