Hi. I can't really tell you how you can tell when someone's having a flashback. I have them myself every now and then. Usually they're visual. I think when someone is having a flashback, they probably kind of freeze. I know I do. I freeze. I'm walking, and suddenly I get a flashback, and I can't breathe properly, and I freeze. Then it's over, and I just feel panicky and tearful. So I think the person would just look upset, maybe... I really can't tell you, trying to help the best I can, sorry... You said you have flashbacks yourself, so maybe if you imagine how you might look to others when you're having one, maybe that would help. I don't know. I feel so useless.
