Males who use opiates for long term pain issues, run the risk of
having their testosterone levels go way down. This might be happening to you, and hence your "scent" has changed.
Some doctors will test you and give you supplemental testosterone if this is happening. Testosterone is also important for your bones!

Opiates and other drugs used for pain can also cause increased sweating. This can alter the bacteria on the skin, and change your "scent".