darvocet withdraw symptoms?

Hello, I was prescribed darvocet for migrains and have taken them for several months. I recently quit taking them all together for fear of becoming depended. I have been ill ever since. The first few days I was vomiting, not being able to sleep, having hot flashes and cold sweats and feeling constantly sick to my stomach. It has now been a week and 1 day and I am still having a problem feeling sick to my stomach. Is this normal? How long to withdraw symptoms last? PLEASE HELP. I can take it as long as there is a end in sight.