First off, welcome to the Pain Management boards
I know that sciatica pain is very painful and can be debilitating. I have only had a couple of flair ups in my life. You need to be aware of any positions that cause the pain to be worse. There are many times when sitting will cause it to be worse especially if the base of the chair is pushing against the nerve in the back of your leg.
Have you seen the doctor that did your back surgery for any type of follow up. If he is not helpful then you should seek out another opinion. What kind of doctor are you currently seeing?
Many times the opiod/opiate medications are NOT very helpful in controlling nerve pain. There are many other medications to treat nerve pain specifically that could be helpful including:
2. Neurontin (gabapentin)
3. Pamelor (nortriptyline)
4. Elavil (amitryptiline)
There are many more but these are the more common ones and used the most. They can be more effective than the morphine you are currently using although they could be used together.
As for the drowsiness you are having, it probably has more to do with the Amrix. I had not heard of this before and had to look it up. It is a muscle relaxant but it says that it should not be used long term. The #1 side effect is somnolence or drowsiness/tiredness. When you add the morphine in the mix I can see how it can be pretty sedating. I would ask your doctor if he plans on keeping you on the Amrix.
Is this combination of meds helping at all? I would at least mention the nerve pain meds to your doctor. I have nerve pain and take Lyrica and many people here on the boards take it as well. Keep us posted.