Phil, I really sympathise with you as IMO there is nothing worse than depersonalisation feelings and sensations. For me they are the most frightening symptom of anxiety. All the things you mention I have had too. Like a feeling of being alive as not feeling 'normal'
and like the world around you is totally alien, or your body and brain is totally disconnected from you. God it is awful. You also analyse every motion and move and are totally sensitive to the things you are doing or going to do, like severe anticipation. I also can completely relate to the music thing/ noise thing. When I was suffering severe anxiety and panic a few weeks ago I couldn't bear any noise around me, particularly in public, like the chatter/conversation of people walking around me in town, kids crying, music, etc and when I was at home, the television being too loud or noisy adverts. It was like having my brain completely overloaded and unable to cope and my thoughts would speed up and panic would rise. Another horrible symptom.
All these feelings are because we are just super, super anxious and normal apparently whilst in that state. It is so hard to advise as I know how hard those feelings are and how difficult it is to carry on doing stuff, but I have to say that, for me personally, keeping on going as normally and riding the feelings was the best thing to do. I think because when we sit and try to not do anything until we feel better, our minds go even more haywire and dwell on the bad symptoms we are feeling and make them worse, whereas just the actions of acting normally can help retrain our mind that everything is ok and this is a feeling that will pass the more we keep acting as normal. (if that makes sense)
I do hope these horrible symptoms pass for you soon.
Debs.x