Go see an orthopedic doctor/surgeon. I hurt my shoulder 8 month's ago. I thought for the first few weeks it would get better. It did a little but I still did not have full range of motion. Long story short, I had a fully torn rotator cuff!! MRI, sonogram confirmed. Had surgery 5 days later. Now 8 month's on, no pain but almost have my full ROM. Doc said it would be a year before it was right again... he was right. Don't take chances and get checked out!!
It is the "pop" sound you heard that makes me think hard.
The longer I live, the more beautiful life becomes. Frank Lloyd Wright