"Something came in the window and stole our child and left behind this shell.” Parents record 11-year-old son’s battle with rage, depression and seizures, and are told by one doctor that his change in behavior may be caused by something called PANDAS. Juju Chang reports for Friday's ABC 20/20 and Nightline on children whose parents say they suddenly developed devastating psychiatric and neurological problems following strep throat. https://abcn.ws/2uMKuNh | ABC 20/20