I Have Been Having Pain In My Right Knee For

I have been having pain in my right knee for about three months now. My doctor believes it to be inflammed miniskas and has given me one shot, which helped some but at night when in bed it hurts every move I make so he has given me an expensive drug I cannot continue to pay for so today he sent me naproxin. Is this drug effective and is it habit forming. Wasn't able to speak to my doctor about it>