I was told by new orthopedic doctor about a year ago that he thought it was stem tip pain. So that was about 19 months post surgery. He suggested a bone growth stimulator as a possible help. I used it faithfully for about 6 months (3 hours per day) and thought I was feeling improvement but that was short-lived and I stopped.
What's funny is that I have multiple friends who all said it was the best decision they ever made and I regret having it done or at least having the older style implant which has a longer stem. But at the time I didn't know there were different types of replacements.