These include specific issues like extreme fussiness / colic, night terrors, and bedwetting. (get-your-baby-to-sleep.com)
Symptoms of shaken baby syndrome typically include extreme fussiness, poor feeding, vomiting, seizures, and a baby may be sleeping much more than usual or hard to wake up (lethargic). (verywellfamily.com)
because I've heard that many infants» extreme fussiness peaks at six weeks and then begins to improve. (thirstiesbaby.com)