For me often before I have a clue whats coming up for my alters I will experience physical symptoms. Sometimes pain other times things like weird rashes, often headaches and nausea also parts of my body will become numb...I have even had bathroom accidents during the night or if I switch in public a frantic need to go. Kind of sucks but now that I know there is almost always a reason it is happening it is not nearly so scary or upsetting.