Can anyone tell me why my 6 week old wakes up screaming?

S • 24. Married. First time Pregnant!

My LO will be out cold literally snoring and drooling and wake up whimpering or screaming bloody murder out of no where.. she’s eaten, she’s not too hot or cold and she’s been changed just before she fell asleep. She freaks out if she’s put down, so I was even holding her. She does this at night time too from time to time. Does anyone know why this happens? I thought maybe gas, but we gave her gas drops after her last feeding. I feel awful every time it happens and it’s hard to know what to do to settle her back down.