Your symptoms are classic for opiate withdrawal. It is common for people to have no problem leaving other substances, only to get caught up in opiates-- they are very addictive medications, particularly for some people.
You should seek out an addictionologist or treatment program. Most people think that they can stop on their own, and waste a few years trying to quit before finally 'giving up' and getting help. Most people make the mistake of thinking that the withdrawal is the biggest proglem, but they find that after the withdrawal is over, and life is getting back to normal... they relapse.
Treatment ranges from residential or outpatient, usually based on twelve step principles but not always. A new option is the use of Suboxone or Subutex, two medications that use the active ingrediant buprenorphine to virtually eliminate cravings and induce remission of opiate dependence... as long as the person takes the medication.
I understand exactly what you are going through. I am going through the same thing right now. I don't know what to do. My wife knows that I take the medication sometimes but not as much as I really do. I am mainly afraid to stop because of my new job. I am trying to support my family and if I am out of work trying to pass this we want have any money. I need somthing or someone to help me.