Startle by big sound?

Phoebe
My baby is around 13 weeks. She gets very easy to be startled suddenly.  A sneeze can make her cry.  And she is upset about going out. Taking her to supermarket always ends up with her screaming. I took her to visit a day care yesterday and she can't stop crying. I don't know how to comfort her. I really hope this will only last for a short period of time.