Pain following a Right Total Knee Replacement

I had a Rt TKR in November 2017, have full flexion, pain free during the day. At night the knee becomes painful 5-6 on a pain scale. I have shooting pains when I move the knee, roll over in bed and get up during the night. If I get up to walk on it the pain leaves within a few minutes. It just does not like me laying down. I had a bone scan and the Impression was-There is mild abnormal active soft tissue inflammation-cellulitis-capsulitis-synovitis present involving the right knee joint. It is believed to be due to a combination of postsurgical inflammation-healing (given that the surgery was performed less than a year ago) and altered stress mechanics due to the presence of the arthroplasty. The implants are in solid. There is no infection as they tapped the knee. My Orthopedist said to wait for 6 months and maybe then repeat the bone scan. I can not take anti inflammatory drugs as I have only one kidney (donated 16 years ago). Has anyone had this problem?