Toddler does not sleep

I need some help . My 15 month old for the past two weeks goes to bed around 7:30 ish and goes down easily but within 10 min she is screaming and doesn’t want to sleep at all. She used to do this when she was 9 months old but stopped and is now back at it . We let her cry it out about 5-7 min and go in her room to calm her down or have to take her out of room and hang with us for a few and she still won’t sleep. Anyone else have issues like this and what helped ? She is not hungry we give her snack and milk before bed and she doesn’t have wet diaper we make sure . We don’t know what the issue is and it’s horrible for us we get no down time