been taking for several yrs off, on for bad headaches, shoulder pain. this medicine is propox n/apap tb 100-650. the substitute darvocet is 100 tab. sometimes I brake them in half too. I don't like to rely on any medicine. I want to quit taking this because I'm scared I'm relying on it. my dr. doesn' t think so, hes a neurologist I go for my migraines. what do you think?