Thank You for a very thorough and detailed response. Much of what you have suggested I am presently doing, although there are a couple of things I will give a go.

I have did as you suggested and had a good prod at my buttock and the pain is reproduced, so I think I've now got a name for it. I am due to see my physiotherapist tomorrow and will discuss this with her. I am presently sleeping on my front, (which is quite unnatural for me) as there is no other position offers me any comfort. I do the pillow thing and the rolled up towel, I think you physiotherapists know all the tricks!!! I am extremely grateful for your advice, it certainly puts my mind at rest. I will continue to keep up the exercises and fingers crossed all will become well.