My Husband Has Been Having Radiating Pain And Stiffness In

My husband has been having radiating pain and stiffness in both leg; mostly in the thigh and calf area. This has been happening off and on for over s month now. And to add insult to injury; yesterday he twisted his left leg and is in nagging pain. I have Pain formula M8 and Voltaren Gel. Is it safe to use on his sprain?