This isn't specifically a pediatric question as there seems to no longer be any primary care experts on the site. :( One day my arm hurt and my range of motion seemed limited. I made a doctor's appt. and saw him the next month. He ordered an xray and concluded later that I had Calcific Tendinitis, but not before having me start physical therapy. After two months of PT my range of motion was restored and pain was reduced but most mornings I still wake with soreness in that shoulder. At my physical 2 months after PT started my doctor decided there was apparently still too much inflamation and gave me the cortisone shot. After the first couple days I felt much better but since than it has begun to be sore again in the morning before my PT routine. How long term are the results of a cortisone shot? Is it typical to continue feeling some pain as inflamation is going down?
I am not accustomed to seeing calcific tendonitis in the peds age group. My answer is therefore very general. Was the injection in the affected area or just into a muscle for a general steroid effect? I suspect into the affected area. Some initial pain due to the injection into an inflamed area can result but after a few days should be better. Steroids can exert a positive effect for a few months, in general.
If your treatment isn't going as you would like, then seeing an orthopedic expert is what I would do if in your shoes.
Good luck, dr. Olson