When will it get better?

My LO is 6 weeks old. Recently she was having 3-4 hours sleep stretches at night and we were able to get some rest. But all of a sudden the last couple days she is hungry all the time, fussy, and wakes up every 1-2 hours at night.

My husband and I are exhausted from sleep deprivation. I feel overwhelmed and down. I know eventually it will get better but when? Are we going through another growth spurt now?