Doctor prescribed me phenergan

My OB prescribed me promethazine. I’m still in my first trimester but whenever I went to look at whether it was safe or not to use it said to not take if you are pregnant. I read on many different medical websites and even asked my pharmacist and they said that usually they’ll prescribe phenergan for women when other medicines have not worked. But besides that they do not recommend pregnant women to take it. So I’m confused on why this is the first nausea medication my doctor told me to take? Does anyone else have any non medicinal things you do to treat your nausea?