You can taper them and reduce withdrawal in that way, provided you have not become psychologically addicted to them, as well as physically dependent (which you clearly are). If you were taking them for valid pain there is probably a greater chance that you can just stop them. If you were taking them to deal with emotional issues, you will likely have a much harder time staying away from them.
Your symptoms are all classic withdrawal symptoms. Believe it or not, they are the relatively 'mild' symptoms; most addicts complain the most about the involuntary muscle movements that are more common coming off higher doses of opiates. You want to look at your daily (24 hour) intake and make a 10-20% reduction every week if you want to avoid withdrawal. The 'cold turkey' method you are using (the name comes from the goosebumps that are also present on cold turkey!) won't kill you, but it is miserable for a few weeks. Clonidine is a prescription medication that can really help; immodium is over-the-counter and will stop the diarrhea. Warm baths for chills and tight muscles, and as soon as you can tolerate it, getting some exercise will all help. The bottom line is that opiate withdrawal stinks.
Really need some help. Not doing too well.