After fighting for over two years I have forgotten some info I used before

As a PS to The 1st post, I was onto this problem here 2 months ago with what apears to be a very good answer from Eileen. I'm back at PT again and there has been no reesolution yet. Walking with a cane now for safety.

You should be able to drop back to the original dose if it were not a PMR problem, as you have been on the higher dose for such a short time. I had sciatica at the beginning of last year in my left leg, it was so painful it took my breath away. I went up to 10mg too, but it made no difference so I dropped back. My GP offered me paracetamol, cocodamyl and naproxen! The only thing that worked for me was physiotherapy. 

Adrenal insufficiency doesn't cause sciatica - almost certainly the first thing you would notice there is increasing profound fatigue. And adrenal insufficiency also has no link with PMR pain.

The most likely cause of your sciatica - if you don't have disc problems, and even then probably in addition to - is muscle spasm due to either myofascial pain syndrome or piriformis syndrome. They are both often found alongside PMR, not part of it but parallel. Physio as such in the form of exercises may not help - it could be other techniques physiotherapists use that are more important such as manual mobilisation of trigger points and spasmed muscles. I have had physios who were aware of the techniques but not all are so good. Someone who is experienced in sports physiotherapy would be the most useful IMHO. The stretching exericises that are commonly suggested are to stretch spasmed muscles - but that will only work if the actual underlying cause of the spasm is also being addressed. In MPS that is trigger points of hard spasmed muscle fibres that can be felt as hard knots in the body of the muscle and which can irritate nearby nerves - in this case the sciatic. I've had steroid shots into those knots - they are formed by concentrations of the same cytokines that cause generalised PMR pain and stiffness so that will work. Whether steroid shots will help sciatica or not depends on the cause and there are needling techniques that don't use steroids that also work in my experience.

As ptolemy says - after 3 days you could have gone straight back to 4 1/2 mg immediately. How fast you do that other 1mg is now dependent on how long you've taken to get this far.