I'm on prednisone for sinus infection. I have a leg cramp from work. Safe to take Aleve (naproxen) for pain on this medication?

Let your doctor know. and see what they say and have it recorded in your chart. Usually it's safe, But your doctor knows your history, other medications, medical conditions, things that would make a better decision if s/he knew about it first to then advise you on it now.