How Long Will It Take to Get Back Pain Relief from Breast Reduction?

I had breast reduction 2 weeks ago for shoulder, neck and back pain. I went from a 36dd to a 36 c. I had immediate pain relief right away. My pain level was cut in half!! I was thrilled. But yesterday, 10 days later it came back full force. My pain level is back up to 6-7. I hope this wasn't for nothing. How come it came back? Does my back just need time to heal? I just don't understand why I would get such immediate relief and then it would come back. I'm not doing anything to aggravate it.