I know where your coming from, i can be normal one minute, next minute i feel fearful, anxious, i feel scared, like feeling that im not part of the world, like i belong somewhere else, i always get a dry mouth aswell when i get this and it can be anywhere, the other day i was shopping for groceries and i felt the feeling coming on, a few minutes later i was crying panicking, rushing around and everyone was looking at me. I never ever suffered from depression or panic attacks before, infact i never understood depression before i got it a few months ago, its definitly mercury.