I asked Dr Gross about steroid injections in the event of some soft tissue issues post surgery. He said that he occasionally recommends cortisone injections, but prefers waiting until one year after surgery in order to give the soft tissue a reasonable amount of time to heal, and then only after giving physical therapy a good try. In the case of my first hip, I had some issues with trochanteric bursitis between 9 and 18 months, but rest and physical therapy took care of it before we got around to the injection option.
Remember that the soft tissue takes at least 18 months to fully heal, so time wise you are only halfway there, and it is not unusual to have issues pop up and then recede. In my case it was about two or three years before I completely stopped having any soft tissue issues.
Best of luck, and I hope things resolve quickly for you.