night/day time reversed

Hey everyone! FTM here & I have an 8 week old who has gone back to her day/night confusion. About a week ago my daughter has been sleeping 3-4 hours at a time at night & she even had a few 5-6 hour sleep stretches which were amazing for my husband & I. This week she is waking up every 2-3 hours & is somewhat fussy (whereas last week she wasn't). 
Is anyone else experiencing this? Does anyone have any light of experience to share? Help me...