That takes time my friend ! Its one of the worst parts of recovery in my opinion ! It will come after you stop with the opiates trust me . Boredom and the lack of joy in doing normal things is hard at times but you will wake up one day and smile again . So keep your eyes on the prize ! Jimmy
First of all, being clean for a month is a lifetime. You have gone through one of the very difficult things in life. So, way to go. It can take people longer than a month to completely recover from opiates and alcohol use. Don't give up.
Secondly, athritis and fibro both can cause depression and fatigue and I would agree with overeasy on looking into some physical therapy. Also, I would talk with your physician about changing antidepressants around. There are many options to choose from. And please come back to update us on how you feel. I'm rooting for you!
Fibro is a real tough one because it can also cause exhaustion- my sis has this. Have you had a physical lately? I would look into that because you should be feeling better, maybe not all the way but definitely better.