Hi bobalog,
Welcome to the forum.
There have been a few threads about Somatic Experiencing on the forum, I think this is probably the longest one:
[DLMURL]https://www.ptsdforum.org/c/threads/somatic-experiencing-have-you-tried-it.22214/[/DLMURL]
You can search to see more threads by using the search box near the top right of each page - untick "this forum only" to pick up threads from anywhere on the site.
As I said in the thread I linked to, I had a related somatic therapy (craniosacral therapy) although not actually somatic experiencing. I think somatic therapy is wonderful, and can't imagine dealing with trauma without it.
The shuddering and twitching is a good sign because it means the tension, although suppressed, is trying to come out. Somatic therapy can facilitate that.
If you go ahead, as with all therapy make sure you see someone properly trained and registered/licensed with a reputable institute or professional body. Also check how much training and experience they have in adult trauma.
Good luck!