Sorry yellowted, I dont know if this person suffered from dissociation at all.
The thing about body memories is that it is buried in the subconscious so you wont be aware or what is triggering you. It just gets hardwired in. Its just the bodies way of coping with the un copeabable. A form of ultimate suppression I suppose.
Another person.... while under sedation for an operation, had these bruises come up around his wrists. Eventually it was traced to being tied up as a kid, but it was something that his mind had buried.
I was sedated for a dental procedure. While unconscious my neck spasms started. I certainly cant fake that.
IT is very hard to deal with the body when it is not doing what we would like. Medicine has come a long way but not so much with the aspects that affect the subconscious.
When my body is doing something that is hurting me...... I ask it what do you want. Sometimes I get an answer.... or it starts crying which short circuits the bodily actions. Tears are a good form of expressing unspoken pain. It just feels like a big jigsaw inside sometimes.
I know I am not giving you solutions. If I could I would tell you how to fix things. Its all a kind of personal journey for every-one. You aren't alone. You aren't faking things either.
Hang in there,