I had the Synvisc One injection on March 7th. The first day was good. Then it started to hurt on the right back side of my knee. It is stiff and hurts when I stand up or use the stairs. I can still walk fine. It appears there is a little swelling and it is slightly warm to the touch. I can still do my 2 mile walk with hardly any discomfort. I can also use a treadmill and stationary bike. I hesitat to go to the doctor because I read that a person needed to give it 30 days or so. The pain is no where near as painful as the original pain that resulted in the injection. Sometimes it is not painful at all. Is this a normal reaction?