Suggest Treatment For Shoulder Pain After Shoulder Surgery

I have just had shoulder surgery and I 'm still having pain. The Dr increased the Hydroco 5-325 mg to Hydroco 7.5-325mg. The tab I started taking today is different from the first ones. The 5's were flat and round and the 7.5 mg are oval. And the marking is M366. The pain is still there. Is the 7.5 mg marked M366---real?