You might want to check with your doctor about PSEUDOGOUT which effects the knee for proper treatments.
(Calcium Pyrophosphate Deposition (CPPD) disease, often called pseudogout, is a type of arthritis caused by calcium pyrophosphate crystals depositing in joint cartilage, leading to sudden, intense inflammation. It primarily affects adults over 60, causing pain, swelling, and stiffness—frequently in the knees—and is commonly managed with anti-inflammatory)
I don't believe there is any side effects from TOPICALLY applied Volteran/Diclofenec. (Get prescription strength 3 or 5% not the 1%). There are good topical CBD from Sageway and Tylenol works great.